Hi Troy Clemons,
Unfortunately, currently the RadRichTextBox doesn't support native watermarking. The only workaround as of now is to make the RadRichTextBox transparent and place a custom background behind the text. However, I have added this to our to-do list and created a PITS feature request for this. You can monitor its progress over here
Let us know if you need any further assistance.
the Telerik team
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