Place chicken breasts in a shallow glass dish or resealable plastic bag. Combine rosemary, garlic, black pepper, olive oil, and salt in a small bowl. Pour mixture onto chicken, cover or seal, and place in refrigerator for 15-20 minutes. Preheat grill for medium-high heat. Place chicken breast on a lightly oiled grill rack and allow to cook for 7 minutes per side. When chicken is no longer pink and juices run clear, remove from heat and serve.