Workaround:

CartesianRenderer renderer = null;

public RadForm1()
{
    InitializeComponent();
    this.radChartView1.CreateRenderer += new ChartViewCreateRendererEventHandler(radChartView1_CreateRenderer);
    LineSeries lineSeries = new LineSeries();
    lineSeries.LegendTitle = "Line 1";
    lineSeries.DataPoints.Add(new CategoricalDataPoint(20, "Jan"));
    lineSeries.DataPoints.Add(new CategoricalDataPoint(22, "Apr"));
    lineSeries.DataPoints.Add(new CategoricalDataPoint(12, "Jul"));
    lineSeries.DataPoints.Add(new CategoricalDataPoint(19, "Oct"));
    this.radChartView1.Series.Add(lineSeries);
    LineSeries lineSeries2 = new LineSeries();
    lineSeries2.LegendTitle = "Line 2";
    lineSeries2.DataPoints.Add(new CategoricalDataPoint(18, "Jan"));
    lineSeries2.DataPoints.Add(new CategoricalDataPoint(15, "Apr"));
    lineSeries2.DataPoints.Add(new CategoricalDataPoint(17, "Jul"));
    lineSeries2.DataPoints.Add(new CategoricalDataPoint(22, "Oct"));
    this.radChartView1.Series.Add(lineSeries2);
    this.radChartView1.ShowLegend = true;
    this.radChartView1.ChartElement.LegendPosition = LegendPosition.Float;
    this.radChartView1.ChartElement.LegendOffset = new Point(200, 95);

    CartesianArea area = this.radChartView1.GetArea<CartesianArea>();
    area.ShowGrid = true;
}

private void radChartView1_CreateRenderer(object sender, ChartViewCreateRendererEventArgs e)
{
    renderer = new CartesianRenderer(e.Area as CartesianArea);
    e.Renderer = renderer; 
}

private void radButton1_Click(object sender, EventArgs e)
{ 
    string filePath = @"..\..\..\exportedChart" + DateTime.Now.ToLongTimeString().Replace(":", "_") + ".png";
    using (MemoryStream stream = new MemoryStream())
    {
        ExportToImage(this.radChartView1, stream, new Size(1000 ,500), ImageFormat.Png, filePath);
    }
    Process.Start(filePath);
}

public void ExportToImage(RadChartView chart, Stream stream, Size size, ImageFormat imageFormat, string filePath)
{
    if (!this.IsLoaded)
    {
        this.LoadElementTree();
    }

    size = Telerik.WinControls.TelerikDpiHelper.ScaleSize(size, chart.ChartElement.DpiScaleFactor);

    Bitmap bmp = new Bitmap(size.Width, size.Height);
    Graphics graphics = Graphics.FromImage(bmp);
    graphics.Clear(Color.White);

    SizeF titleSize = graphics.MeasureString(chart.Title, chart.ChartElement.TitleElement.Font, this.Width);

    if (chart.ChartElement.TitleElement.TextOrientation == Orientation.Vertical)
    {
        float swap = titleSize.Height;
        titleSize.Height = titleSize.Width;
        titleSize.Width = swap;
    }

    RadRect titleRect = new RadRect(0, 0, titleSize.Width, titleSize.Height);
    RadRect legendRect = new RadRect(0, 0, size.Width, size.Height);
    RadRect chartRect = legendRect;

    switch (chart.ChartElement.TitlePosition)
    {
        case TitlePosition.Top:
        case TitlePosition.Bottom:
            titleRect.Width = size.Width;
            break;
        case TitlePosition.Right:
        case TitlePosition.Left:
            titleRect.Height = size.Height;
            break;
    }

    chartRect.X += chart.View.Margin.Left;
    chartRect.Y += chart.View.Margin.Top;
    chartRect.Width -= chart.View.Margin.Horizontal;
    chartRect.Height -= chart.View.Margin.Vertical;

    if (chart.ShowTitle)
    {
        switch (chart.ChartElement.TitlePosition)
        {
            case TitlePosition.Top:
                legendRect.Y += titleRect.Height;
                chartRect.Y += titleRect.Height;
                legendRect.Height -= titleRect.Height;
                chartRect.Height -= titleRect.Height;
                break;
            case TitlePosition.Right:
                titleRect.X = size.Width - chart.ChartElement.TitleElement.Size.Width;
                titleRect.Height = size.Height;
                legendRect.Width -= titleRect.Width;
                chartRect.Width -= titleRect.Width;
                break;
            case TitlePosition.Bottom:
                titleRect.Y = size.Height - chart.ChartElement.TitleElement.Size.Height;
                titleRect.Width = size.Width;
                legendRect.Height -= titleRect.Height;
                chartRect.Height -= titleRect.Height;
                break;
            case TitlePosition.Left:
                titleRect.Height = size.Height;
                legendRect.X += titleRect.Width;
                chartRect.X += titleRect.Width;
                legendRect.Width -= titleRect.Width;
                chartRect.Width -= titleRect.Width;
                break;
        }
    }
    chart.View.Layout(chartRect);
    renderer.Draw(graphics);
    if (chart.ShowLegend)
    {
        switch (chart.ChartElement.LegendPosition)
        {
            case LegendPosition.Right:
                if (chart.ChartElement.TitlePosition == TitlePosition.Right)
                {
                    legendRect.X = titleRect.X - chart.ChartElement.LegendElement.Size.Width;
                }
                else
                {
                    legendRect.X = size.Width - chart.ChartElement.LegendElement.Size.Width;
                }

                legendRect.Width = chart.ChartElement.LegendElement.Size.Width;
                chartRect.Width -= legendRect.Width;
                break;
            case LegendPosition.Bottom:
                if (chart.ChartElement.TitlePosition == TitlePosition.Bottom)
                {
                    legendRect.Y = titleRect.Y - chart.ChartElement.LegendElement.Size.Height;
                }
                else
                {
                    legendRect.Y = size.Height - chart.ChartElement.LegendElement.Size.Height;
                }

                legendRect.Height = chart.ChartElement.LegendElement.Size.Height;
                chartRect.Height -= legendRect.Height;
                break;
            case LegendPosition.Left:
                legendRect.Width = chart.ChartElement.LegendElement.Size.Width;
                chartRect.X += legendRect.Width;
                chartRect.Width -= legendRect.Width;
                break;
            case LegendPosition.Top:
                legendRect.Height = chart.ChartElement.LegendElement.Size.Height;
                chartRect.Y += legendRect.Height;
                chartRect.Height -= legendRect.Height;
                break;
            case LegendPosition.Float:
                legendRect.Width = chart.ChartElement.LegendElement.Size.Width;
                legendRect.Height = chart.ChartElement.LegendElement.Size.Height;
                double xRatio = size.Width / this.Size.Width;
                double yRatio = size.Height / this.Size.Height;
                legendRect.X = (chart.ChartElement.LegendOffset.X * xRatio) + ((chart.ChartElement.TitlePosition == TitlePosition.Left)
                                                                               ? titleRect.Right : 0d);
                legendRect.Y = (chart.ChartElement.LegendOffset.Y * yRatio) + ((chart.ChartElement.TitlePosition == TitlePosition.Top)
                                                                               ? titleRect.Bottom : 0f);
                break;
        }
    }
    
    if (chart.ShowLegend)
    {
        float xTransform = (float)legendRect.X - chart.ChartElement.LegendElement.ControlBoundingRectangle.X +
                           ((float)legendRect.Width - chart.ChartElement.LegendElement.ControlBoundingRectangle.Width) / 2f;
        float yTransform = (float)legendRect.Y - chart.ChartElement.LegendElement.ControlBoundingRectangle.Y +
                           ((float)legendRect.Height - chart.ChartElement.LegendElement.ControlBoundingRectangle.Height) / 2f;
        graphics.TranslateTransform(xTransform, yTransform);
        chart.ChartElement.LegendElement.Paint(new RadGdiGraphics(graphics), chart.ChartElement.LegendElement.ControlBoundingRectangle, 0f,
            new SizeF(1f, 1f), true);
        graphics.ResetTransform();
    }
 
    RadGdiGraphics radGraphics = new RadGdiGraphics(graphics);

    if (chart.ShowTitle)
    {
        radGraphics.DrawString(chart.Title, GetTitleDrawRectangle(ChartRenderer.ToRectangleF(titleRect), titleSize,
            chart.ChartElement.TitleElement.TextAlignment), chart.ChartElement.TitleElement.Font,
            chart.ChartElement.TitleElement.ForeColor, chart.ChartElement.TitleElement.TextParams.CreateStringFormat(),
            chart.ChartElement.TitleElement.TextOrientation, chart.ChartElement.TitleElement.FlipText);
    }

    if (imageFormat == ImageFormat.Emf ||
        imageFormat == ImageFormat.Wmf)
    {
        Metafile metafile = new Metafile(stream, graphics.GetHdc()); // file is created here
        using (Graphics g = Graphics.FromImage(metafile))
        {
            g.DrawImage(bmp, Point.Empty);
        }

        metafile.Dispose();
        graphics.ReleaseHdc();
    }
    else
    {
        bmp.Save(stream, imageFormat);
    }

    chart.View.Layout();

    Image img = Image.FromStream(stream);
    graphics.DrawImage(img, new Point(0, 0));
    img.Save(filePath);
}

private RectangleF GetTitleDrawRectangle(RectangleF drawArea, SizeF textRect, ContentAlignment textAlignment)
{
    switch (textAlignment)
    {
        case ContentAlignment.BottomCenter:
            return new RectangleF(new PointF(drawArea.X + (drawArea.Width - textRect.Width) / 2f, drawArea.Bottom - textRect.Height), textRect);
        case ContentAlignment.BottomLeft:
            return new RectangleF(new PointF(drawArea.X, drawArea.Bottom - textRect.Height), textRect);
        case ContentAlignment.BottomRight:
            return new RectangleF(new PointF(drawArea.Right - textRect.Width, drawArea.Bottom - textRect.Height), textRect);
        case ContentAlignment.MiddleCenter:
            return new RectangleF(new PointF(drawArea.X + (drawArea.Width - textRect.Width) / 2f, drawArea.Y + (drawArea.Height - textRect.Height) / 2f), 
                textRect);
        case ContentAlignment.MiddleLeft:
            return new RectangleF(new PointF(drawArea.X, drawArea.Y + (drawArea.Height - textRect.Height) / 2f), textRect);
        case ContentAlignment.MiddleRight:
            return new RectangleF(new PointF(drawArea.Right - textRect.Width, drawArea.Y + (drawArea.Height - textRect.Height) / 2f), textRect);
        case ContentAlignment.TopCenter:
            return new RectangleF(new PointF(drawArea.X + (drawArea.Width - textRect.Width) / 2, drawArea.Y), textRect);
        case ContentAlignment.TopLeft:
            return new RectangleF(drawArea.Location, textRect);
        case ContentAlignment.TopRight:
            return new RectangleF(new PointF(drawArea.Right - textRect.Width, drawArea.Y), textRect);
        default:
            return new RectangleF(drawArea.Location, textRect);
    }
}