You don't "drop" the cheese in, you activate on the pot like you would a door or a chest. You don't need to remove the cheese from your inventory or anything like that.
I presume you've talked with Ri'bassa already, and gone through all of his dialog options. He should have already told you about the prophesies (you may have to bribe up his disposition to get him to tell you everything.) Your last journal entry should be "Ri'bassa has suggested I stay at the Border Watch Inn, which apparently has a large collection of cheeses."