RadFixedDocument document = new RadFixedDocument();
RadFixedPage page = document.Pages.AddPage();
page.Size = new Size(600, 800);
FixedContentEditor editor = new FixedContentEditor(page);
editor.Position.Translate(defaultLeftIndent, 50);

Block block = new Block();
block.InsertText("PDF");

editor.DrawBlock(block);

Block border = new Block();
border.GraphicProperties.StrokeColor = RgbColors.Black;
border.GraphicProperties.IsFilled = false;
border.GraphicProperties.IsStroked = true;
border.GraphicProperties.StrokeThickness = 1;
border.InsertRectangle(new System.Windows.Rect(block.Measure()));

editor.DrawBlock(border);