Here is how it works:
  1. Install Outlink app
  2. Using the app attach external links to the products you want. In your case external links will point to dr's website.
  3. Add to Cart button on Shopify will be replaced with External link pointing to dr's website
  4. Your visitors can click on External link and get redirected to dr's site
  5. You get paid as per your commission rate terms with dr
Hope this helps.