This will allow the users to scroll through the tiles in all rows when the available height is insufficient.

WORKAROUND:
 class CustomPanorama : RadPanorama
    {
        RadScrollBarElement vScroll;

        protected override void CreateChildItems(Telerik.WinControls.RadElement parent)
        {
            base.CreateChildItems(parent);

            this.vScroll = new RadScrollBarElement();
            this.vScroll.ScrollType = ScrollType.Vertical;
            this.vScroll.StretchHorizontally = false;
            this.vScroll.StretchVertically = true;
            this.vScroll.MinSize = new System.Drawing.Size(16, 0);
            this.vScroll.Alignment = System.Drawing.ContentAlignment.TopRight;

            this.PanoramaElement.Children.Add(vScroll);

            this.vScroll.ValueChanged += new EventHandler(vScroll_ValueChanged);
            this.PanoramaElement.GroupLayout.RadPropertyChanged += new Telerik.WinControls.RadPropertyChangedEventHandler(GroupLayout_RadPropertyChanged);
            this.PanoramaElement.TileLayout.RadPropertyChanged += new Telerik.WinControls.RadPropertyChangedEventHandler(GroupLayout_RadPropertyChanged);

            this.ScrollBarAlignment = HorizontalScrollAlignment.Bottom;
        }

        void GroupLayout_RadPropertyChanged(object sender, Telerik.WinControls.RadPropertyChangedEventArgs e)
        {
            if (e.Property == RadElement.BoundsProperty && sender == this.GetCurrentLayout())
            {
                UpdateVScroll();
            }
        }

        protected override void OnSizeChanged(EventArgs e)
        {
            base.OnSizeChanged(e);
            UpdateVScroll();
        }

        private void UpdateVScroll()
        {
            vScroll.Maximum = this.GetCurrentLayout().Size.Height;
            vScroll.LargeChange = Math.Max(0, (int)(this.Size.Height - this.PanoramaElement.ScrollBar.Size.Height));

            if (vScroll.LargeChange >= vScroll.Maximum)
            {
                vScroll.Visibility = ElementVisibility.Hidden;
            }
            else
            {
                vScroll.Visibility = ElementVisibility.Visible;
            }

            if (this.PanoramaElement.ScrollBar.Visibility == ElementVisibility.Visible)
            {
                vScroll.Margin = new System.Windows.Forms.Padding(0, 0, 0, this.PanoramaElement.ScrollBar.Size.Height);
            }
            else
            {
                vScroll.Margin = new System.Windows.Forms.Padding(0);
            }
        }

        void vScroll_ValueChanged(object sender, EventArgs e)
        {
            this.GetCurrentLayout().PositionOffset = new System.Drawing.SizeF(0, -this.vScroll.Value);
        }

        private LayoutPanel GetCurrentLayout()
        {
            if (this.ShowGroups)
            {
                return this.PanoramaElement.GroupLayout;
            }

            return this.PanoramaElement.TileLayout;
        }

        public override string ThemeClassName
        {
            get
            {
                return typeof(RadPanorama).FullName;
            }
            set
            {
                base.ThemeClassName = value;
            }
        }
    }