Thank you for writing.
If I have understood your requirement correctly, you can use the ViewCellFormatting event of the RadGridView to set the text orientation of the header cells. Here is a code snippet which demonstrates this:
sender, CellFormattingEventArgs e)
e.CellElement.TextOrientation = Orientation.Vertical;
If this is not what you want to achieve, I would kindly ask you to provide some more information and if possible a screen shot or a sketch, so I can get a better idea of your requirements.
I am looking forward to your reply.
All the best,
the Telerik team