NL20 KK vs Unknow

Prima, $0.10/$0.20 No Limit Hold'em Cash, 6 Players
Poker Tools Powered By Holdem Manager - The Ultimate Poker Software Suite.

Hero (MP): $21.50 (107.5 bb)
CO: $22.57 (112.9 bb)
BTN: $16.02 (80.1 bb)
SB: $20.90 (104.5 bb)
BB: $37.62 (188.1 bb)
UTG: $37.09 (185.5 bb)

Preflop: Hero is MP with K K
UTG folds, Hero raises to $0.60, CO folds, BTN calls $0.60, 2 folds

Flop: ($1.50) 8 T 6 (2 players)
Hero bets $1, BTN calls $1

Turn: ($3.50) J (2 players)
Hero bets $2.60, BTN calls $2.60

River: ($8.70) J (2 players)
Hero checks, BTN bets $4.30, Hero calls $4.30

Results:

Villian was Unknow , I played this hand @ Ano Tables . What you think about this line ?
Should i bet/fold , bet/call the river or its ok to check/call ? What you think about the bet sizing flop/turn ? THX