:-)
I believe that all of the REL subs are powered subs, so what your amplifier will be driving is not the 4 ohm impedance of the sub's driver, but rather the input to the sub's amplifier. That will be a very high impedance, perhaps as much as 100K for the speaker-level inputs in some cases, IIRC, and so your amplifier essentially won't know that it's there.
I'd just connect the sub to whichever tap on the amplifier you determine your Meadowlark's sound best with, which probably (but not necessarily) will be the 8 ohm tap.
Also, keep in mind that the high input impedance of the sub, and the correspondingly small amount of current that it will draw, mean that you don't need heavy gauge speaker wire for the connections between amplifier and sub.
Best regards,
-- Al