I created the gist how do I add it to my profile?
Your nip07/nostraddress is invalid. Suggest you set up a nostr well-known on your website and update your profile so people can trace your package signature on zap store to something you own like https://blitz-wallet.com .
https://www.marks.wiki/p/custom-nostr-verification-using-github
You can also sign a github gist from your github account using NIP39 proving your npub is tied to the developer of your app and paste the URL into your npub profile under "github gist with signature"
Discussion
It appears only amethyst (android) supports nip-39, but it is equally valid to simply add it to your profile description . E.g.
{{{
GitHub: https://github.com/yourusername
Gist Proof: https://gist.github.com/yourusername/GistID
}}}