Ben's SEO Blog: How to Add Meta Tag Fields to Your Content Types in Drupal

So you have your Meta tag module installed and all the default meta tags configured. However, you still need to tweak the meta tags for a specific page, but the meta tag fields aren't showing up in the edit interface. Here's how to get those to show up for the various content types.

Go to Manage > Structure > Content Types. This displays the Content types listing page.