Rosemary oil can be used daily for acne. It depends on the severity of your acne as well as your skin's sensitivity. Apply rosemary oil as soon as you get out of the shower after rubbing it into affected parts of your body, like your face, neck, back, and chest. Rosemary oil can also be applied to areas with scars caused by acne (such as on the chin, jawline, and forehead). Apply only a thin layer though to avoid dryness.