An antenna is classified as Right Hand Circularly Polarised if the driven element radiates an electromagnetic wave in which either the electric or the magnetic vector executes a clockwise circle perpendicular to the path of propagation with a frequency equal to that of the wave.
The term hand is used as it refers to the formation of a "thumbs up" with a persons left hand, where the thumb indicates the direction of wave propagation, and the fingers curl in the direction of the circular rotation.