My image is quite tagish, but villain is a huge fish: 73/20, so it doesn't matter

I think I missed an opportunity to bet the turn.
Now how much to bet on the river? $12? What do we do if villain c/bombs?

No-Limit Hold'em, $0.50 BB (5 handed) - Hold'em Manager Converter Tool from FlopTurnRiver.com

BB ($153.46)
UTG ($26.60)
Hero (MP) ($66.22)
Button ($22.20)
SB ($48.82)

Preflop: Hero is MP with K, Q
UTG bets $2, Hero calls $2, Button calls $2, 1 fold, BB calls $1.50

Flop: ($8.25) 8, Q, 6 (4 players)
BB checks, UTG checks, Hero bets $6, 1 fold, BB calls $6, 1 fold

Turn: ($20.25) A (2 players)
BB checks, Hero checks

River: ($20.25) K (2 players)
BB checks, Hero ???

Total pot: $20.25