Using RDM6300 to Read FSK 125Khz Fob

I have a Keri PKT-10X keyfob which I believe operates with FSK 125Khz. I’d like to be able to read it.

I am new to Arduino but curious if I could modify an RDM6300 RFID reader to modulate frequency so that it can produce both the 125Khz and 113.6Khz signals it needs (I think).

Any guidance would be appreciated.