On your User Interface, there's buttons to select Skills (and I don't mean open the window that allows you to add points to your skills, this one is on the upper row), or to use Potions (next to the skills button previously mentioned). First, click the type you want to add a hotkey for. Then, with your mouse pointer hovering over the skill or potion you want to hotkey, press one of the Function keys. (F1-F12) This should put a little letter and number(s) on the skill or potion you were hovering your pointer over. If it was a skill you hotkeyed, pressing the hotkey will make the skill the one you activate when you right click. If it was a potion, pressing the hotkey immediately drinks one if you have any in inventory. You can only bind one skill OR potion to a given key, not both to the same key, and I don't know of any ways to bind a key other than a Function key to either of those. If you want to, this same method works for switching weapons, but each weapon would need a hotkey that isn't bound to a potion or skill. *Note: I could never add a hotkey to F10, and I recall hearing that it just plain isn't an allowed key for hotkeying skills or potions.
(I hope I was clear enough)