Anandakanda 1.2.83

1.2.83

choṭikā darśayedaṣṭa paścādādhāramāharet /
tatraivāvāhayedagnimaṇḍalaṃ bījamūlakam //

One should display eight snaps of the fingers; afterwards, one should bring the base.
Right there one should invoke the fire mandala whose root is the seed-syllable.