RFD900+ PWM GPIO ports?

So, does anyone know how the advertised “PWM Input/output” ports work on the RFD900+? I always assumed it was just plug a pwm signal into one of the GPIO ports and output it from the RX side and vice versa, but I tried that with a servo tester and didnt really get any output. I didnt even know that SiK radios were capable of this, but they did advertise it.

For some reason there isnt any mention of PWM in the rfd900+ documentation either.

I guess i’m failing to understand what this means:

“GPIO: 6 General purpose IO (Digital, ADC, PWM capable).”

from the RFD900+ page on rfdesigns