The Form XObjects are supported in RadPdfViewer. In case anyone has messed up this feature with the one for interactive forms and form filling, please, vote and subscribe to the corresponding item at http://feedback.telerik.com/Project/143/Feedback/Details/197877 .
I have a pdfviewer bound to a richtextbox like in your samples. But I want to keep the wpf viewer in fit to window scaling mode while changing the content of the richtextbox. Right now the pdfviewer will rescale to 100 % on each update.
The issue is closed as duplicated to the following item: http://feedback.telerik.com/Project/143/Feedback/Details/141105-tiling-patterns-are-rendered-wrong-when-some-transformation-is-applied