What is the Ruling on the Payment of Zakaatul-Fitr in the form of Cash?

This should not be done. No. The view which is held by the jumhoor (majority of the scholars) is that it is to be paid in the form of food and not in cash. That's because the Messenger ﷺ gave food and likewise his companions and the majority of the people of knowledge. So, it should not be paid in cash, rather, it is obligatory for Zakaatul-Fitr to be in the form of food. This is what is obligatory.