It's = Fn + Space.
I had to use Shift-PrtScrn to do screen recording with ShareX, and realized that the printscreen key is not on here. Thanks to a google search, and another site for a batch script to stop the recording with a timer.
For the script:
@echo off
set /p time_h="Enter Recording timeout(H): "
set /p time_m="Enter Recording timeout(M): "
set /p time_s="Enter Recording timeout(S): "
set /a result_h = %time_h% * 60 * 60
set /a result_m = %time_m% * 60
set /a result_s = %time_s%
echo %result_h%
echo %result_m%
echo %result_s%
set /a time = %result_s% + %result_m% + %result_h%
echo %time%
timeout /t %time% /nobreak
start "" "C:\Program Files"\Sharex\sharex.exe -ScreenRecorder