from what I can see, it says that it "supports" 3270 terminal emulators.
Now the big question is whether you want to treat the PCOM screen like a windows screen, or if you want to try and interface using the venerable HLLAPI protocol.
I think the PCOM screen is really just text. I doubt RFT would be able to identify individual fields and treat them as separate objects like it does with buttons and edit boxes in windows. With HLLAPI, you can get to individual fields, so they may have added a layer that exposed 3270 fields as objects.
My guess would be that the 3270 support is a plugin/addon that you have to install. Then you'd configure it to work with your emulator.
A small piece of advice from someone who has been doing HLLAPI since 1991: The mainframe screen will report that it is "done" several times before it really is. There is NO final "now I'm really done" byte that gets sent.