1. Login to GitHub with the account that shall perform the integration (regular account works)
2. Click on the avatar and select Settings
3. Click on Developer settings
4. Click on OAuth Apps
5. Click on New OAuth App
6. Fill in Name any name will do
7. Fill in Homepage, either full callback or to the main RINT screen ending with /secure/RestClientAction.jspa
8. Fill in the Callback url which you copy from the authentication settings. more info here OAuth2
9. Click Save

Scopes

https://developer.github.com/apps/building-oauth-apps/understanding-scopes-for-oauth-apps/

Authorize URL

https://github.com/login/oauth/authorize

Access Token URL

https://github.com/login/oauth/access_token