The only difference in heaving to with a fin is bringing the boat to a full stop before letting the bow swing down wind and putting the helm up. If the boat isn't stopped it will just keep fore reaching. You can usually balance the sails by adjusting the main, if the bow wants to come up you need to depower the main. We used to heave to in all sorts of small dinghies between races, I've never sailed a boat that won't heave to.
I don't understand how you could heave to with a single sail without fore reaching, it's the balance of jib against rudder and main.
"Just call me TB"