The full PDF contains dozens of mantras. Here are the critical ones:
: Performing this ritual fulfills one's Pitru Rina (debt to ancestors). Yajurveda Amavasya Tharpanam In Sanskrit Pdf
Om Pitamahabhyo Namah, Pitamaha Swadha, Tarpayami. The full PDF contains dozens of mantras
Here is a brief overview of the ritual: