As the RadDocking uses internally TabControl, the exception occurs in the project, nevertheless it should be fixed in the Last Internal Build. You can downloaded from our website and give it a try.
Also in order to send us the simple project you have prepared you just need to open a new support ticket and attached the project in it.
As we are not aware of the issue with the RadDockingAutomationPeer it would be great if you can also give us a simple steps to reproduce.
the Telerik team