Here is a link to a great NPC explainer on RFM:
https://npcwomen.dynamic.omegafi.com...pdate-2017.pdf
Basically, each chapter will invite X PNMs back to each round. X is determined by RFM (Release Figure Methodology), a program that uses each chapter's return rate (the number of PNMs on a chapter's list who want to return to them next round i.e. do not list them in their "drop" chapters) to figure out how many PNMs need to be invited to each round for that chapter to make quota at the end of recruitment.
If a chapter has a 90% return rate they are going to be required to release more PNMs than a chapter that has a 60% return rate because they are, in essence, "assumed" to have a 90% chance of a PNM on their first bid (quota) list accepting so they do not need as many women on their second list (this means fewer PNMs need to be invited to pref for the 90% chapter to make quota). This math is applied to the invites for all rounds.
