You can add Gist (formerly Convertfox) or Intercom Chat widgets to your projects using the "General Settings" card in your projects settings or on the Publish screen.
Just select your chat service from the pulldown and enter your project ID.
Gist (formerly Convertfox)
How to find your Gist project or app ID
Please make sure to set your project domain to "app.involve.me" or make sure "app.involve.me" is whitelisted for your project under Settings > Whitelist Domains.