How to target Facebook users with products they viewed without purchasing

I am trying to work out this issue for some weeks now. I even contacted Facebook but they said to contact Stack Overflow.

How are you successfully targeting Facebook visitors with the same product after they viewed it and left from your website?

For example: Mr. A visits example.com which is an e-commerce site. Views Product A then goes to Product B and then exits from the site. The next day Mr. A will see Product B in the Right Column/News Feed Ads.

I have a hunch that it has something to do with firing the Custom Audience Pixel with the Product B id data but not sure how to implement that code in the FB Custom Audience Pixel.

Also note: I have already configured the Product Feed and the product catalog work is all done.