Should I bet this river

[sk_man]

Villian is a little loose PF and very passive. I only had about 35 hands on him at the time, so it's not the strongest read ever.

After the turn, I put him on Ax, Kx or a pocket pair. I haven't done the math yet, but I think I should have bet against a player this passive. I'm a little weak on the river.

Party Poker 1/2 Hold'em (9 max, 9 handed) FTR converter on zerodivide.cx

Preflop: Hero is UTG+1 with A[img]/images/graemlins/heart.gif[/img], K[img]/images/graemlins/spade.gif[/img].
1 fold], Hero raises, 4 folds, Button calls, 2 folds.

Flop: (5.50 SB) A[img]/images/graemlins/club.gif[/img], 4[img]/images/graemlins/heart.gif[/img], 2[img]/images/graemlins/club.gif[/img] (2 players)
Hero bets, Button calls.

Turn: (3.75 BB) K[img]/images/graemlins/club.gif[/img] (2 players)
Hero bets, Button calls.

River: (5.75 BB) 7[img]/images/graemlins/club.gif[/img] (2 players)
Hero ?