PokerStars 0.50/1.00 Hold'em (6 handed) from (Format: Bet The Pot)

Preflop: Hero is SB with , .
UTG calls, 1 fold, CO calls, Button calls, Hero completes, BB checks.

Flop: (5 SB) , , (5 players)
Hero bets, BB folds, UTG calls, CO calls, Button calls.

Turn: (4.50 BB) (4 players)
Hero bets, UTG folds, CO calls, Button folds.

River: (6.50 BB) (2 players)
Hero bets, CO calls.

Final Pot: 8.50 BB

I'd prefer a check on the river...that 4c is a pretty ugly card. Yes, you'll occasionally get a little extra value from something like K9 or a mid pair by betting (and it looks like you might've here), but I think most of the time he's either going to raise or fold to your bet. And if he was hanging in with something silly like 98, your check might induce a bluff where a bet would make him fold. Plus, if he has something like KJ or KQ (yes, it would be passive on his part, but I've seen people just call down in such spots), he'll probably check the river, saving you a bet.

Anyways, I put him on 66.

-TW