You can start with a VERY tiny amount, like a few grains, and build up from there. I have always been able to chow on a spoonful or more, but my allergy problems were well under control before I started consuming it.
I recommend getting some from a local beekeeper. The grains should be brightly colored, well-hydrated, fresh looking. I would ask when they were gathered & packaged. You don't want old dried-out ones. I keep mine in the refrigerator.
I wouldn't bother with a multivitamin that contains it. Its most powerful properties come from being fresh and raw.