BTN is a loose player
Should I check the turn? Should my fop bet be bigger to get rid of small pairs?

I bet big on the river since I had the Kh to see if I could get rid of Ax - but that may be flawed since he calls alot.

Any help is welcome. Thanks!

MP: 60.38 BB
MP+1: 28.41 BB
CO: 37 BB
BTN: 40.34 BB
SB: 6.92 BB
BB: 36.69 BB
Hero (UTG): 37.23 BB
UTG+1: 44.92 BB

8 players post ante of 0.14 BB, SB posts SB 0.5 BB, BB posts BB 1 BB

Pre Flop: (pot: 2.64 BB) Hero has Kc Kh
Hero raises to 2.5 BB, fold, fold, fold, fold, BTN calls 2.5 BB, fold, fold

Flop : (7.64 BB, 2 players) 4d 2d Ah
Hero bets 2.91 BB, BTN calls 2.91 BB

Turn : (13.46 BB, 2 players) 7h
Hero bets 4.37 BB, BTN calls 4.37 BB

River : (22.2 BB, 2 players) 5h
Hero bets 16.15 BB, BTN calls 16.15 BB

BTN shows 7c 7s (Three of a Kind, Sevens)
(Pre 20%, Flop 9%, Turn 95%)

Hero shows Kc Kh (One Pair, Kings)
(Pre 80%, Flop 91%, Turn 5%)

BTN wins 54.49 BB

For starters, what tournament is this? (buy-in, live or online, what site etc) It's good to share those details along with the hand so posters have more context to provide feedback. Secondly, I think preflop and flop seem good, but what was our intention with the turn bet? Regarding river, I think it's good process to try and do 2 things when you bluff-

1) rep a credible range (at least 4-5 value hands you'd take said line with)

2) know what you're trying to fold out

While you do have the Kh blocker here at the nut flush which is helpful, the KQh and KJh are really the only true value hands you're repping on this river with such a large bet outside of 33 for a straight which likely doesn't play turn that way. You also can't even rep AK/AQ with this line and river bet sizing cause you wouldn't be betting those hands for value on such a scary river. To the second part (know what you're trying to fold out), I think rec players/lower stakes players don't enjoy folding top pair (especially if it's an Ace) so I'd try to avoid bluffing those types of villains in these spots in general.

OTR you basically turn your kings into a bluff, telling BTN you either catched a runner runner flush or has a 3. (If you had AA you would have bet bigger on the turn, right?)

If you don't have a very loose image that's not a very trustworthy story, since you opened from UTG. Of course a loose player might have a bunch of Ax-hands that might fold. He can also have a busted diamond flush draw, but you won't achieve anything by betting big into him then.

A loose player will probably also call all his low to middle pairs on the button. When he calls two streets against an early opener on this board he will often have sets I believe .

I think you should have checked the turn. As played the river should be a check. You wrote yourself he "calls a lot" meaning you really don't know if he will fold out enough Ax-hands. And him folding those is probably the only thing that could make this big river bet profitable.

Should you use your kings as a bluff catcher if he bets when you check? That I don't know, but probably not. Busted diamond draws are probably the only thing you bet, unless he's super loose and super sticky.

Two solid responses.

Not much you can do here against a player on the BTN who calls on this flop.

I think your flop sizing is fine.

The turn sizing I don't like much. I would bet about 60% pot (if I bet) because the diamond didn't hit and a gutter didn't get there. A flush draw would likely be called by this Villain as he would likely call with an A. So a call here would be my last bet unless a K hits the river. In general here I typically check/fold though against most Villains. Check/calling would likely require a call on the river as well and it would be crippling. If it went check/check on the turn I likely call a river bet which I think would often be a bluff after a draw missed.

As played the turn call by Villain could be anything. Villain is getting implied odds to call with just about any draw and any Ax.

As played I would check the river and probably not call a decent sized bet (though a diamond flush draw that missed would generate some bluffs). I guess my read on Villain would be the major factor. Does he overbluff or underbluff and if I haven't seen much betting on late streets what kind of player do I think he is?

The river is a disaster because a gutter got there and a backdoor flush also got there. If I was going to bluff here I would jam because we have the K but I wouldn't bluff here.

On this flop UTG v BTN checking and betting slightly smaller than what you bet with my range would be my strategy. KK mostly check but small bet seems reasonable. Turn I would view this hand as a slam-dunk checking candidate - with your sizing opponent should not find any folds w/ Ax, KK is not a hand requiring much protection and hands that we are already ahead of such as 99/88/66 should be folded out.