What is the monetary amount that must be given for a vow to feed 100 poor people, and is it permissible to give it in another country, such as Saudi Arabia, given that one resides in America and is unable to find poor people there?

Whoever vows to feed a poor person must give him what suffices to feed him in a moderate state, which is estimated between a quarter of a saa' and half a saa'. A saa' is estimated at three kilograms. It is permissible to transfer the vow to another country.