How does food work in Ultima VII?

Solution 1:

Base Game

Double click the food item and a reticule will come up. Just like using potions or bandages. Then click on someone with it.

Exult (highly recommended!)

Assuming you're running Exult, just press 'F' and a reticule will appear having selected a (?) random (?) food item from your party's storage. *

Also in Exult, 'K' will try every key you have. 'P' will use a lock pick.

You can see if they're hungry if they have a picture of a knife and fork at the bottom of their character sheet.

* Using 'F' seems to use as many items as necessary to fill them up, as IME, they always say they're full if I try to feed them again, but that could be because I always carry a sack completely full of venison.