Full Tilt No-Limit Hold'em, $1.00 BB (9 handed) - Full-Tilt Converter Tool from FlopTurnRiver.com

Button ($117.15)
Hero (SB) ($100)
BB ($177.60)
UTG ($92.55)
UTG+1 ($27.60)
MP1 ($144.55)
MP2 ($42.75)
MP3 ($113.90)
CO ($111.25)

Preflop: Hero is SB with K, 7
UTG calls $1, 6 folds, Hero calls $0.50, BB bets $3, UTG calls $2, Hero calls $2

Flop: ($9) 5, 8, 9 (3 players)
Hero checks, BB bets $5, UTG calls $5, Hero calls $5

Turn: ($24) 6 (3 players)
Hero checks, BB checks, UTG bets $10.50, Hero calls $10.50, 1 fold

River: ($45) A (2 players)
Hero checks, UTG bets $23, Hero raises to $81.50 (All-In), UTG calls $51.05 (All-In)

Total pot: $193.10 | Rake: $3

Results:
Hero had K, 7 (straight, nine high).
UTG had 10, 7 (straight, ten high).
Outcome: UTG won $190.10

Some reads on the other players would be helpful, especially UTG.

Question about the river check/raise, what hands do you think he is calling with?

yeah reads are important here...
its the one hand that would of beat you... cant really kick yourself for that one i gues...
what range did you put him on?

I guess i would of expected rivered 2 pair..

I'm worried about is splitting other 7's and increasing the rake (and the occasional cooler)

It's more than just finding out "if you did something wrong", this hand has a lot of options with the Flushdraw+Gutshot, and maybe there's a more +EV play to make.