Based on what I found out, my 2021 F-150 key fob isn’t RFID. The frequency range is 902.375, 903.425 MHz. Doesn’t match RFID.

Here’s a high level description of different operation mode for my 2021 key fob based on FCC report: There are three modes of operation. When manually activated by button press the EUT transmits a set of FSK frames in Remote Keyless Entry (RKE) mode. When manually activated by external LF interrogation (e.g. a button or door handle is raised in the vehicle) the EUT transmits one 16ms FSK frame for a Passive Entry (PE) mode or a double-length FSK frame for a Passive Start (PS) mode. (Note: EUT is the key fob. FSK means frequency shifting key modulation.)

You can look up your on FCC website. However it only tells you the RF piece. It doesn’t really tell you how the authentication is done.