If you understand the concept of an endogeneity, you will realize that the reserve ratio requirement is essentially meaningless. You're confusing theories of law with theories of economics. Even in the absence of required reserves a prudent local banker will always keep reserves. If he doesn't, he will soon be out of the banking business, regardless of the law. The concept here is that money is a 'rate' or a relationship, not a quantifiable thing.
Loans increase effective demand.
The repayment of loans decrease effective demand. Loans increase the rate of spending. The repayment of loans decrease the rate of spending. Money can be defined in the broad sense to be any form of IOU, i.e. promise to pay, whether in legal tender or not. Well, it does lead to be the concept of endogeneity, which seems to elude you.