Tried it across one of my sites. Doesn't work.
Everybody's a boss on Facebook. Everyone's a hustler over there.
While applying for a payday loan online is a recourse taken in a period of crunch. Not many are proud of it (or about loans of any form). These decisions are often taken behind closed doors. Yes, there are habitual borrowers, but that's a different section altogether.
The point is, most people will shy away from linking their Facebook account with anything that has to do with them borrowing money. So it doesn't work. No matter how clearly you state that your site's name is not going to show up in their feeds.