Hi!
That's a mighty old bug you found. Thanks for the feedback.
Get the source code for PDFsharp/MigraDoc, open the file RtfDocumentRenderer.cs and locate method "RenderInfo()".
Insert one new line of code:
Code:
_rtfWriter.StartContent();
_rtfWriter.WriteControl("f", 2); // This line is new.
_rtfWriter.WriteControl("info");
Change will be included with the next NuGet packages (and no, there is no ETA for that).
I don't know if there is a way to work around that issue without changing MigraDoc - besides the hacky method of saving to a stream and inserting "\f2" before writing to a file.