Protection against EMI for an RFID reader
Note that RFID works with a magnetic field. The antennas are basically a pair of (magnetically) coupled inductors.

The shielding materials usually only block the electrical field and not the magnetic field. It is still possible that the shielding will work though, you will just have to try.

If the shielding does not work you could try shielding with a sheet of metal which does block the magnetic field. If a permanent magnet sticks to a piece of metal then that metal will do the job. For example: copper is non-magnetic and will not work. Steel is magnetic and will work.

The close proximity of the (magnetic) shield might prevent the RFID antennas from working as it influences their inductance and therefore the resonance frequency of the antenna + RFID circuit. Then you want a solution without using a shield. What I would then suggest is keeping the tracks with the (clock) signals on your PCB as far away as possible from the antenna. Also make the loops small because a long track/loop (signals always travel in loops, they go back through the common ground!) will radiate a magnetic field like a loop antenna. You might have to design a new PCB to include all these changes!