This was covered by an FCIF moons ago but remember, it's a take off AND landing. When you log a landing it assumes and logs a take off to count toward your currency. That's why the sim is (was) called a "three and three". So, when you give an RFO the landing, you have to give him the T.O. too....so for all intents you're swapping roles between the F.O. and the RFO. I did this in the past, but never without consulting my F.O. and getting his approval, even though I was giving up my leg. "The weather looks good, the RFO can have the landing", doesn't comply.