In the trigger actions, the action is
Player - Turn player flag on / off
So it will look like this:
Player - Turn 'gives bounty' on for player X
Then in the object editor, inside the unit, there are two fields. Bounty base, and Bounty dice, both which help determine the ammount of gold the unit will give.
Joueur - Turn 'donner recompense ' On For Joueur 1