You are correct the reason images are not rendered is that they are actually WMF images. Those images are not supported out-of-the-box from RadRichTextBox.
The good news is that we have a demo in our SDK repository on GitHub which demonstrates how to implement an image decoder for that image format. You can find the demo here
. Please note, the demo has a reference only to the DocxFormatProvider assembly. In order to test it with a Rtf file, you should add a reference to the Telerik.Windows.Documents.FormatProviders.Rtf dll
I hope this helps.
If you have further questions, I'll be glad to assist you.
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