I f'ed this one up. I should have raised. But shoudl it have been on the
flop or the turn? And how much?

Ultimate Bet No-Limit Hold'em, $.25 BB (10 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

UTG+2 ($7)
MP1 ($23.25)
MP2 ($36.60)
Hero ($24.85)
CO ($34.45)
Button ($19.45)
SB ($13.20)
BB ($9.85)
UTG ($56.90)
UTG+1 ($23.70)

Preflop: Hero is MP3 with A, K.
3 folds, MP1 raises to $0.85, 1 fold, Hero calls $0.85, 3 folds, BB calls $0.60.

Flop: ($2.65) K, 4, 2 (3 players)
BB checks, MP1 bets $1, Hero calls $1, BB folds.

Turn: ($4.65) T (2 players)
MP1 bets $2.25, Hero calls $2.25.

River: ($9.15) 7 (2 players)
MP1 bets $9.15, Hero calls $9.15.

Final Pot: $27.45

Results in white below:
MP1 has 7s 7d (three of a kind, sevens).
Hero has Ac Kh (one pair, kings).
Outcome: MP1 wins $27.45.