Villain is 15/4, but only over 27 hands...
Pretty sure this is a call, but how is my line/sizing in general? I'm a cash game newbie, so might be posting some other hands...

No-Limit Hold'em, $0.10 BB (6 handed) - Hold'em Manager Converter Tool from FlopTurnRiver.com

saw flop

BB ($9.65)
Hero (UTG) ($18.79)
MP ($17.52)
CO ($10.66)
Button ($15.19)
SB ($5.34)

Preflop: Hero is UTG with 4 , 4
Hero bets $0.40, 3 folds, SB calls $0.35, BB calls $0.30

Flop: ($1.20) 10 , K , 4 (3 players)
SB bets $0.10, BB calls $0.10, Hero raises $1, 1 fold, BB calls $0.90

Turn: ($3.30) 8 (2 players)
BB checks, Hero bets $2.50, BB calls $2.50

River: ($8.30) 2 (2 players)
BB bets $4.50, Hero calls $4.50

Total pot: $17.30

If my math is right, his final bet leaves him with $1.25. That strikes me as odd for his line. If he made the (nut) flush I think he'd put it all in. Sounds like he's bluffing... I think in this game, unless you have a really good read, you gotta call.

maybe more on the turn...line overvall is fine though.

this is like never a bluff but whatever we're getting asinine pot odds at 10nl

turn bet for $3 which means we stick him in on river

Mash pot button on the flop.
Both villains are well covered and it makes the entire hand much easier to play.