You have tagged the question with SharePoint Foundation so I assume you are not using SharePoint Server product.
Ratings are NOT available in SharePoint Foundation. They are available in SharePoint Server standard and enterprise version only.
See the feature comparison here: http://sharepoint.microsoft.com/en-us/buy/pages/editions-comparison.aspx
Based on your comments and link in your question, it seems looks like it should be available to you unless you started with blank site template. I just figured it out. Also check: http://the-sharepoint.blogspot.com/2012/01/where-is-my-rating-feature.html
You can enable RATING feature alone by following Powershell command.
Enable-SPFeature 915c240e-a6cc-49b8-8b2c-0bff8b553ed3 –URL http://yoururl.com