Main villain in hand is otb. He seems to be playing standard, but good. Earlier made a good lay down against me when I shoved river after board paired deuces( I rivered boat) he said he folded nut straight. I have him pegged as solid reg. Sb is secondary villain in hand. He has been getting unlucky since he got here.
Stacks are as follows:
Hero ~$350
main villain barely covers.
Sb~$100.
Bunch of limpers sb completes. I look at the almighty 23ss. I check option.
Flop is k95. All spades. Sb checks. I lead $10?(size)?
Everyone folds to button he calls. Sb calls.
Turn jh. Sb checks I bet again. $40 this time(size)? Button tank calls. Sb calls pretty quickly. After looking like he's gonna muck.
River 10d. I?
At this point I feel like some has single As. Not sure who though. Also feel like other guy could have flopped a set, or turned a straight, or have flopped flush also. I just couldn't see both players calling this much heat without flush draw less than the nfd. And they cant both have that. So what does other guy have? Tough spot I'm stumped.
Also, I always have a tough time when I flop a semi strong made hand like this in bb. Especially when I would have folde this garbage if I could have.

Value bet again. Much more likely that you're playing against pairs with FDs than better flushes who never raised to charge other draws. If they hit unlikely straights, they'll prob pay off at least a half-pot bet. Naked As are folding, of course.

Sizing looks fine except that we don't know how many limpers are in a bunch, so Flop bet is unknowable.

Bet for sure IMO. >Half pot