Not only the RTP, but the 2k RTP graphic style. As you can see here:
http://www.multimediaxis.de/threads/...Tutorials-usw?
... we have many people who are editing the 2k RTP. You are allowed to use those, you can create your own sets IF it looks like it comes from the 2k RTP. You can use all music and sounds you want, no restriction here.