1Heat oven to 300°F. Spray 17x12-inch half-sheet pan with cooking spray. Place popcorn in large bowl.
2In 1-quart saucepan, heat syrup, butter, rosemary, orange peel and salt to boiling over high heat, stirring frequently. Cook 2 minutes without stirring. Pour syrup mixture over popcorn, stirring to coat completely. Spread popcorn in single layer in pan.
3Bake 15 minutes. Stir; bake 3 minutes longer. Cool completely, about 30 minutes. Store in airtight container.