How To Make A Reg File

I want to make a reg file to automatically change the key KMD_EnableBrightnessInterface2 from 1 to 0 in the following string. This way I can use it on another computer.

HKEY_LOCAL_MACHINE \ SYSTEM \ ControlSet001 \ Control\Class \ {4d36e968-e325-11ce-bfc1-08002be10318} \ 0000 \KMD_EnableBrightnessInterface2

The folder 0000 contains many key values.
I can right click the folder 0000 and export it but I don't want to export the whole folder.
When I right click the key: KMD_EnableBrightnessInterface2 it does not give me the option to export it. I only have the option to Modify/Modify Binary Data/Delete/Rename
That's the only key I need to export

Your advice would be appreciated.

Kind regards
Chris

Registry_.JPG