Real band is a full featured DAW so it should be totally possible to use an external (not in Real Band) VST to play the midi parts...

However, having said that... I use Sonar.

Everything ends up in Sonar. I use BB to create and write.... I use RB to render the BB tracks to the RB tracks and into audio. I export the RB tracks into Sonar. Since I know the BPM, I set Sonar to that and then if I need to record additional audio tracks or use a VST triggered from a midi track, it is a simple process to use any of the number of VST synths I have in my DAW computer in Sonar to create that track.

I have never liked the DAW in RB since when I got RB I had already been familiar with Sonar fro many years and was used to working in it.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.