This handprint with the right hand touching the knee and the fingertip touching the ground is called "touchdown print", which is unique to Buddha Sakyamuni, so it must be Buddha Sakyamuni.

Touching the ground is because on the day when the Buddha became a Buddha on the site, Papman, the demon king, came to make trouble. The Buddha touched the ground with his hand, called out a firm god, and testified that he had won the Buddha's fruit, which made the demon king retreat.