I wasn't aware that PDAwin included RF in any of their official releases.

I had proposed a method for sending RF using the audio output jack. In my tests, it worked with an iPAQ 3635 but was marginal with a Dell x5. I thought that some simple modification would probably allow it to work but that was about the time I ended up in cardiac care and I never followed up later with Dusan at PDAwin. Perhaps he has gone forward on his own - it's not particularly difficult but the RF transmitter used is critical.

What RF frequency do you want to use?