Garudapurana 1.11.6

1.11.6

ṣaḍaṅgena tataḥ kuryātsākṣādyena harirbhavet /
dakṣiṇāṅguṣṭhamārabhya madhyāṅguṣṭhandale nyaset //

Then one should perform it with the six limbs, by which one directly becomes Hari, / beginning with the right thumb, one should place it in the center of the petal of the thumb.