Since: Dec 04, 2007
So let me see if I have this right: The keys are responding properly in Reaper, and you want to record the audio (built-in sounds) coming directly from the keyboard.
If you check the back of the keyboard, you should see a couple ports for audio out. Usually a left and right channel. You'll want to connect those to your line-ins on your audio interface or sound card, and make sure that you are actually recording the audio coming from the keyboard. Making sure the track in reaper is armed, and the audio 1&2 option is selected, and you're getting a proper audio signal.
Since you're recording the audio straight from the keyboard, the midi is actually irrelevant since the signal will travel from the audio outs to the line-ins
However, if you have a midi track with midi notes/data that is sending signals to the keyboard, then you'll need 2 tracks to get the sounds. 1 track for the midi that is sending data to the keyboard, and 1 to record the audio coming from the keyboard. (I think that's right at least)
Hope that helps! Keep us posted :)