Adding the Open Graph Protocol in your Blogger or Blogspot Blog
A few notes:
1. og:locale Should probably actually reflect the blog's locale instead of just being a hardcoded string. Unfortunately, Blogger only gives us en-us with a hyphen, instead of an underscore, so that won't work.
2. If you're using your blog as a personal profile, you may consider changing the second og:type from website to profile and adding your personal information
3. og:image Is only supplied if Blogger finds an image in the current post. However, not supplying og:image is invalid. You could provide an alternate image of your blog logo, or a Gravatar.
<!-- Begin Open Graph metadata -->
<b:if cond='data:blog.pageType == "item"'>
<meta content='article' property='og:type'/>
<meta expr:content='data:blog.title' property='og:site_name'/>
<meta expr:content='data:blog.pageName' property='og:title'/>
<b:if cond='data:blog.postImageThumbnailUrl'>
<meta expr:content='data:blog.postImageThumbnailUrl' property='og:image'/>
</b:if>
<b:else/>
<meta expr:content='data:blog.title' property='og:title'/>
<meta content='website' property='og:type'/>
</b:if>
<meta expr:content='"en_US"' property='og:locale'/>
<meta expr:content='data:blog.canonicalUrl' property='og:url'/>
<!-- End Open Graph metadata -->
After adding the code above simply copy and paste the button or widget code anywhere in your website.
Cheers!