Hmm that is strange as I had it on my system.
Open your Oculus app and on the left hand side click Settings.
In the right hand window click on Beta and then enable the “Public Test Channel”
Now check your registry settings again as that entry should be there and ensure it is as shown below, assuming your Oculus app is installed to C drive
If it isn’t there I guess you could create the relevant entry by creating the directorys “OpenXR” and “1” and then create a new String Value named ActiveRuntime and modify its value to C:\Program Files\Oculus\Support\oculus-runtime\oculus_openxr_64.json
Check in windows explorer, also, that the file exists in that location.