How do I map right alt to emit Fn?

[qubbit]

Hi, how do I map my right alt key to act like the macOS Fn key? I could not find this key in the configurator

• Device:

Kira

• Firmware Origin:

Default firmware

• OS:

macOS

• Version:

"bcdDevice" = 1222

• Reproduction Steps:

Can't reproduce this issue because the Fn key does not exist in Kira

• Resulting Issue:

[haata]

Fn is tricky as it's actually covered in the "Vendor Specific" portion of the USB spec.
Apple coded their OS such that only "Apple" keyboards can officially send the Fn key (at least the last time I checked a few years ago).

hasu of TMK has info here on the subject: https://github.com/tmk/tmk_keyboard/wiki/FAQ-Keymap#applemac-keyboard-fn