The memory leak is reproducible when the main thread is too busy to dispose objects used by RadDocument internally. Thus, the RadDocument instances are kept alive in the memory. 

Workaround: When the scenario includes back processing of documents: Start different threads responsible to perform the required operations and use the following code:

Dispatcher dispatcher = Dispatcher.CurrentDispatcher;
dispatcher.BeginInvokeShutdown(DispatcherPriority.Normal);
Dispatcher.Run();

anywhere in the background thread processing the RadDocument.