River decision with set

[VBCurtis]

Artichoke Joe's 15/30. I'm a tourist to the area, been at the table one orbit. Villan has been loose (played half his hands) preflop, haven't seen him raise postflop in the 10 hands I've been there for.

One limper to me, I raise KK. Both blinds and limper see K42 rainbow flop.

Checked to me, I bet, SB and limper call.
Turn 9 completing rainbow. Check, I bet, both call.
River 5. Check, I bet, SB raises, limper folds.

I...?

What hands might villain have?
-Curtis