How to set up lead source tracking in Infusionsoft Landing Page?

Hello, how to setup the lead source tracking in a proper way with infusionsoft landing page? There isn’t much information available on the web.

We have tried the following link, but it seems that this is for web forms: http://www.jordanhatch.com/how-to-use-lead-sources-the-right-way/

Also with this one, the information seems to be outdated…
https://www.monkeypodmarketing.com/leadsources-simplifying-sanity/

Please help!