When you say the text is double-spaced, are you referring to the line-spacing property of the paragraphs? If this is the case, we have not encountered such issue before and the XAML you pasted does not seem to be the one to blame. That said, may I kindly ask you to open a support ticket and attach one of the files you are importing, so we can further investigate the problem?
On a side note, I can see that you've set the FontFamily
property of the editor. However, in order to set default font settings to a RadRichTextBox, you should also set the DocumentInheritsDefaultStyleSettings
property to true as explained here
I'm looking forward to hearing from you.