Well 'Support' might be the wrong word. What I mean is that the controls should resize in a consistent way based on the Windows Forms scaling settings etc. For example the RadTextBox resizes with Windows Forms Font scaling, while the CheckBox does not.
Another area are the container controls. I get the feeling that some Telerk container controls behave inconsistently when docked or anchored, especially when used within User Controls and other containers such as RadDock or RadPageView. In my App, this can usually be fixed by placing a Standard Panel controls in between the container and the contained controls.