Yes, you can!

Mac

If you're using Mainstage, here's a tutorial video.

You must set up IAC MIDI drivers to send midi from RMS Keyboards to your DAW/VST plugin:

1. Open your Mac’s Audio MIDI Setup Window and view the MIDI window

2. Double click on IAC Driver

3. If its not checked, check the ‘Device is online’ option

4. Under Ports, clear any available items and then add a port (see attached screenshot for how this window should look)

That will make the IAC Driver active. Now the steps to make the two softwares talk:

1. Launch RMS Keyboards

2. In the patch you wish to replace, click the ‘External Tab’ button

3. Under Device, choose ‘IAC Driver IAC Bus 1’

4. Now go to your target VST/DAW and make the sure the midi input for the instrument or channel is '‘IAC Driver IAC Bus 1’’

You’re now ready to play. Hotkeys are maintained and the DAW/VST will not sound while you are playing other RMS Keyboards patches.

Windows

Note that though we've tested this in office, this method utilizes third party software that we can't troubleshoot or officially support. Test this functionality hard before venturing into performances with it. You'll need a program like Loopbe1 (bottom of page). Here's an example using Kontakt and Loopbe1 and a video tutorial.

1. Install LoopBe1

2. Open LoopBe1

3. Open Kontakt

4. Click File > Options

5. Select the MIDI tab on the lefthand side

6. Under Inputs, assign LoopBe Internal MIDI to Port A

7. Close Options

8. Load your instrument of choice

9. Open RMS Keyboards

10. Enter Edit Mode

11. Navigate to instrument you'd like to replace

12. At the bottom of the instrument's fader, select External.

13. In this menu, select LoopBe Internal MIDI and specify the MIDI channel you're utilizing for the instrument in Kontakt

14. Hit OK

15. Enjoy your external software synth in RMS Keyboards

16. As always when you make changes, File > Save