I created a comment plugin from https://developers.facebook.com/docs/reference/plugins/comments/
It doesn't have an application id. How can I moderate it?
Or if it must have an ID, how do I put an application ID to an existing comment plugin?
Add your id to your meta data
To moderate, you need to list yourself as an admin. To do this, simply include open graph meta tags on the URL specified as the href parameter of the plugin. These tags must be included in the of the document. Include
<meta property="fb:admins" content="{YOUR_FACEBOOK_USER_ID}"/>
The same process for the app id
If your site has many comments boxes, we strongly recommend you specify a Facebook app id as the administrator (all administrators of the app will be able to moderate comments). Doing this enables a moderator interface on Facebook where comments from all plugins administered by your app id can be easily moderated together. You can choose to specify either fb:app_id or fb:admins, but not both. This tag should be specified in the .
<meta property="fb:app_id" content="{YOUR_APPLICATION_ID}"/>
It's all there in the document you linked https://developers.facebook.com/docs/reference/plugins/comments/