In a greased 8x8x2-inch foil pan, arrange raw potatoes. Stir together margarine or butter, rosemary, and chili powder. Pour over potatoes; toss to coat.
Arrange preheated coals around a drip pan in a covered grill. Test for medium-hot heat above the pan. Place foil pan containing potatoes over the drip pan. Cover and grill for 25 minutes. Add chives; cover and grill for 5 to 10 minutes more or until potatoes are tender. Season with salt and pepper, if desired. Makes 4 side-dish servings.