Again, my river play is poor

[KitCloudkicker]

Live 10/20 full.

I limp 77 utg. 3 more limpers, blinds check.

Flop is 5 [img]/images/graemlins/club.gif[/img] 3 [img]/images/graemlins/club.gif[/img] 3:spade. SB leads, BB folds, I raise, two folds, button calls two cold, SB calls.

Turn 6[img]/images/graemlins/diamond.gif[/img]. SB checks, I bet, both call.

River is an A [img]/images/graemlins/spade.gif[/img].

SB checks, this is an obvious bet right?