Well, to be honest, I don't think you'll find much. Who would be writing a book about using a specific scope model? You have the scope's manual, and there's resources about using scopes (I actually don't know a good book, but there's some good appnotes and whitepapers).
.. and then in German?
I have an RTB2k and can answer your questions in German if you want (although PMs might be more appropriate for that on an international forum like this). But for discussions
in German about using a scope, using the RTB, and finding the book you're looking for,
mikrocontroller.net might actually be a better place.
If English is fine after all, your best bet might be to simply ask your questions about scoping technique and tips&tricks here, instead of looking for a book that answers them all. Most of those techniques are fully transferrable between scopes anyway, and there's a sufficient number of RTB users on eevblog to answer specific UI questions or point out limitations of the RTB.
OTOH, R&S
are marketing the RTB2000 for the educational market, so they might actually have course material. I didn't see anything after a quick google, but it might be worth a shot to ask them? Try info@rohde-schwarz.com, or contacting
Rich from R&S USA here on eevblog by PM.