Prepare four foil squares large enough to fold over one potato each. Spread butter onto foil in a large enough area that the potato will be completely covered when rolled up. Sprinkle salt, garlic, pepper, and Italian seasoning evenly over foil. Roll each potato in the foil; puncture the package (including the potato) with a fork or knife a few times.
Grill for 1 hour, or until soft, turning the potatoes often.