To add it to your iPhone, execute this command as "root" on the Terminal App.
curl -fsSL https://okanon.github.io/cydia/gpg | apt-key add - && mv /etc/apt/trusted.gpg /etc/apt/trusted.gpg.d/okanon.gpg && apt update
If you need "stable" repository add the following url to Cydia
If you need "legacy" repository add the following url to Cydia.
Please refer to the official reference for a basic description of Cydia repository hosting. In this section, I'll explain in detail how to handle the GPG key in the Cydia repository and how to create a repository using it.