Poker Stars, $0.02/$0.05 No Limit Hold'em Cash, 6 Players
Poker Tools Powered By Holdem Manager - The Ultimate Poker Software Suite.

Hero (SB): $5.02 (100.4 bb)
BB: $5 (100 bb)
UTG: $5.35 (107 bb)
MP: $13.16 (263.2 bb)
CO: $4.46 (89.2 bb)
BTN: $5 (100 bb)

Preflop: Hero is SB with Ks As
2 folds, CO raises to $0.15, BTN folds, Hero raises to $0.50, BB folds, CO calls $0.35

Flop: ($1.05) 9h Ts 8c (2 players)
Hero bets $0.55, CO calls $0.55

Turn: ($2.15) Kc (2 players)
Hero bets $1.10, CO calls $1.10

River: ($4.35) 6d (2 players)
Hero ?

Villain unknown

What should I do on the river? If I gii, do I get called by worse? Just check-fold then or what?