Copilot Custom API Plugin. Adding a Header Item

Question

I'm creating a copilot api plugin for one of the apps my org uses. I retrieved the openAPI spec file from the app's manufacturer and I've created a new declarative agent in VSCode with the teams and kiota plugins. I've also registered the Basic auth value in the teams vault per the documentation. I'm having trouble tho because when I test this it seems copilot doesn't have access to the API. I know there is another header value for a clientid that the API requires but I can't figure out how to incorporate that in the files. Any help would be greatly appreciated.