[bombcar]

Reserve requirements (unless they go to 100%, but then you can't loan at all off deposit accounts) don't prevent the bank from "loaning out money already loaned" but they do help reduce the chance of a run.

[marcosdumay]

They don't prevent money multiplication, they control money multiplication.

If a country has reserve requirements that are larger than the banks safety margins, the central bank has complete control on the size of M1.