Realtracks are all audio. If you're not using an external keyboard or a Ketron to output your midi sounds - In prefs>audio check reroute midi to vsc/dxi. Then don't worry about that.

Back in your seq file, under the audio tab, select Merge Audio and VSTi/DXi tracks to Stereo just as Seeker suggested. It will ask you where you want to put the new wave file. Put in the same folder where you want to save all your original song seq files, call it My Songs or whatever. Add another folder inside that main one with the song name so you can easily find all files for each of your songs (seq, wav. etc.)when needed.

Close RB. Open Audacity and choose file>open go to your file folder you made and open the file. When you're done with it export to mp3 saving it where ever you want.