I wouldn't consider the RWR to have an "Effective Range"......regardless of what the emitter is, if THAT has enough range to emit radar that hits the F16 RWR, it will show up. RW Receivers are on both Front and back of the F16 with blind spots on top and bottom. Remember, the RWR is a Receiver...not an emitter. Looks like the receiver supports scanning in the 6-20GHZ Low/High band ranges.
As far as Emitter support, I would guess anything in DCS with an active radar would show up whether identified or Unknown. If you are looking for a list, check the F16 Manual page 594.
SubZ3r0's post in What can be detected by RWR, what can't? was marked as the answer