Thank you for writing.
Please refer to the following help article which demonstrates how to customize the context menu of RadTreeView. You can use either the default menu items, or you can add your own with the desired functionality executed upon click: http://www.telerik.com/help/winforms/treeview-context-menus-modifying-the-default-context-menu.html
Let us know if you have any other questions.
the Telerik team