'The right hand' signifies the whole of a person regarding intellectual power and faith. 'To place the right hand on the head,' signifies putting it first.

(参考: Apocalypse Revealed 605)

605. To receive from it a mark on their right hand and on their foreheads. This symbolically means that no one is acknowledged as a Protestant Reformed Christian but one who accepts that doctrine in faith and love.

To receive a mark means, symbolically, to be acknowledged as a Protestant Reformed Christian, or to be among those who confess what the doctrine teaches. The mark is an acknowledgement that the person is such a one, and also a confession that he is such. The right hand symbolizes everything in a person relating to the power of his intellect, thus to his faith; for the right hand symbolizes a person's power (no. 457). The forehead symbolizes everything in a person relating to the power of his will, thus to his love; for the forehead symbolizes love (no. 347).