We currently do not support RTAI. Earlier versions (1.x) did, but limited time and other development priorities mean we no longer focus any effort on maintaining our RTAI/COMEDI interface.
If you need to use RTXI with RTAI, the old source code is still available for you to use. Just remember that you will need to compile and install an RTAI-patched kernel and the COMEDI drivers for you data acquisition card on your own. You can find the old code in our git history: