Thank you for writing.
I will suggest to use the AutoSizeColumnsMode
property of RadGridView
set to Fill
. This way the columns will fill the grid and they will automatically resize together with the control.
More information regarding sizing the columns can be found here: http://www.telerik.com/help/winforms/gridview-columns-resizing-columns-programatically.html
I hope that you find this information useful. Let us know if you have any other questions.
the Telerik team