Right. The missing keys means you must add that particular key into the config.plist.
If the key says 'Kernel > Quirks > Missing Key:SetAPFSTrimout' then you go to Kernel, Quirks
and add the missing key underneath like this:
View attachment 523230
Most keys are set using boolean method ie. yes/no but some could be string or number value also. But if you are using the sample.plist as the basis, all you need to do is make a copy of the sample.plist and transfer over your existing settings (whatever they are) into the config.plist.
Have you generated your SMBIOS serials yet? Such as UUID, ROM and board serials? If not you will need those too under PlatformInfo - Datahub. The sections where they are marked * Generate serial ** are where you need to put your existing SMBIOS serial values if you have them already. If not you will need to generate them using SSDTPrGen. :
View attachment 523231
If you are updating your config.plist to OC 0.6.6. you'll also need to download the Opencore release for 0.6.6.
The download link is under the Assets link under 0.6.6. You need the Release version, X64 files >
https://github.com/acidanthera/opencorepkg/releases
For the full list of settings needed for your configuration you should refer to the Dortania guide here for Kaby Lake: