pi phi ?!

IDK where you read that because a RIF is what Pi Phi calls their recommendation form and it's what they need sent to them, not actual letters. Every sorority has their official form and the rec writers use those and it keeps everything easier for everybody, so your rec writers really aren't sending letters they are sending in forms. Your rec writers probably already knew about the RIF but you can double check with them to make sure they used the official form.

The whole Rec/LOS/RIF thing can be confusing because it means different things for each sorority. The way it's written on the panhellenic website may be why you'd think it's two different things, but that's because the RIF can be informational only OR info plus recommendation (the "letter" you're thinking of). RECS/RIFS said it best - your rec writers should know what's required, but it's also good advice to double-check with them that they used the official form.