Right Hand or Left Hand?

You may have seen retour covers. Some of the retour covers are stamped with a hand sign or stuck with a sticker depicting a hand. How many of you have paid attention to the hand sign? Is the right hand or left hand being depicted? Well, I notice that most of the postal authorities worldwide use right hand sign. I show below two retour covers with hand sign. The retour cover from Taiwan has right hand sign, and the retour cover from New Zealand has left hand sign.

Retour cover from Taiwan showing right hand sign

Retour cover from New Zealand showing left hand sign