How yo assign a Leadsource to an order form?

Hi Guys,

We recently joined Infusionsoft and we are setting everything up but I cant figure out whats the best way to track leadsources for new direct to pay customers.

We are running ads in many ad networks and we want to track the perfomance of each one through the existing ROI reporting at IS. This seems easy to do if you opt in contacts first but we sell our subscription directly, so I havent found a way to pass a LeadSource value to the order form.

I’ve read that parameters can be passed through the url like this:

Would that work for order form pages?