Spray four square foil pieces with cooking spray. Spread potato slices onto the center of the foil pieces. Top with 1 chicken breast. Sprinkle 1 tsp. taco seasoning over each chicken breast. Top each breast with cheese, and then 2 T. salsa. Seal foil into little pockets. Bake each pocket at 400 degrees for 40-50 minutes. Serve with a dollop of sour cream.