Wholesale/Retail site looking for a way to identify the site a buyer came from

Sorry if the title isn’t too clear. What I want to do is to have a generalized image on a retailer’s site that links to my wholesale/retail site. If a buyer clicks on the image on the retailer’s site, comes to my page and make a retail purchase, I want to know where the buyer came from so I can pay the retailer his share of the purchase.

I’m using the Shopkeeper theme if that helps.

I can’t find where WooCommerce will handle this out of the box and have, thus far been unable to find a plugin that will do it. So if anyone knows of such a thing, I would appreciate your help.

Thanks in advance for any help/advice.
Sp