Assalamualikum warahmatullahi wabarakatuhu, when expiating an oath by feeding the poor through a charitable organization is it obligatory to mention to the organization that this feeding of the poor is because of an oath that was broken?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

You must inform the people in charge of the charitable organization that this feeding is an expiation so that they would not think that it is a general charity, as in this case, they would spend it in a way other than the recipients of expiation.

Allah Knows best.