@polosrestaurant basic rfid will not support a 4 diget pin, the basic ones only use a 10 diget serial/id number of the fob.
Am MSR or Barcode should be able to support 4 digets.
MSR reader wise I have had issues with cheap readers which dont come with utility when it comes to the ‘return’ at the end.
Most barcode readers have a simple set of barcodes to enable/disable the return function which is usually on by default.