First of all, this RMS file is not a real player file. It is a file that can be used with the Sheet Music Now viewer app. The viewer app is being largely replaced with online tools and downloadable MP3 files. It is still available for select platforms and can be found here.
Not all titles have the ability to be transposed, but for those that do we recommend that you use the online transposition capability of the website. For more details click here.