25NL Flop Set, river bet size question

[TreeFarm]

Only seen 18 hands with villian, 72/0/.6 over that many. His small stack size made me question what bet to make on river, flush draw not calling any bet, not sure how a 9 would, which just leaves him calling with an A. How do you bet this river, make a small couple dollar raise and hope for re-raise, or someone with that vpp just put him all in on river with still less then a pot sized bet?

As for other streets as the preflop raiser the 1.5 bet is pretty much standard for what I would make with a cbet here, had I called pre I would probably bet closer to pot size. Looking back perhaps should have bet 5 on the turn, fold out more flush draws and better set up push on river.

Poker Stars, $0.10/$0.25 NL Hold'em Cash Game, 6 Players
LeggoPoker.com - Hand History Converter

Hero (MP): $38.40
CO: $16
BTN: $25
SB: $18.25
BB: $7.20
UTG: $24.20

Pre-Flop: 3[img]/images/graemlins/club.gif[/img] 3[img]/images/graemlins/heart.gif[/img] dealt to Hero (MP)
UTG folds, <font color="red">Hero raises to $0.75</font>, CO calls $0.75, 2 folds, BB calls $0.50

Flop: ($2.35) A[img]/images/graemlins/diamond.gif[/img] 9[img]/images/graemlins/diamond.gif[/img] 3[img]/images/graemlins/spade.gif[/img] (3 Players)
BB checks, <font color="red">Hero bets $1.50</font>, CO calls $1.50, BB folds

Turn: ($5.35) 2[img]/images/graemlins/heart.gif[/img] (2 Players)
<font color="red">Hero bets $4</font>, CO calls $4

River: ($13.35) 8[img]/images/graemlins/spade.gif[/img] (2 Players)
<font color="red">Hero ???