Facebook Pixel in child theme?

Catch Kathmandu Pro: Hello, I've tried using several different plugins to paste the Facebook Pixel code into the header without success. I found instructions for pasting it into header.php -- not using a plugin -- (http://www.sweetcapri.com/adding-facebook-pixel-code-to-your-wordpress-website-without-plugin/) but the suggestion is to put it into the parent theme instead of the child theme. Can you advise, please?