I've attached a screenshot of what the comment box should look like after the admin tags have been added:
At the top, you'll see the Moderator View and Settings buttons which let you make some changes to the widget on that page or across the whole site. Additionally, beneath each comment is a moderator drop-down.
I'm not sure why that's not happening to you, but it may be a caching issue from Facebook. You can try the Facebook Linter tool which will re-scan the page for any new Open Graph tags. Facebook will normally re-scan your page every 24-72 hours, so all your comment boxes will be updated in time, but until then, just throwing the URL in the following tool may just fix your issue for specific pages until the re-scan occurs:
developers.facebook.com/tools/lint
Hope that does it for you, but if not, you know where to find us!