All you have to do is to install Firebug for mozilla.

Install here

Press F12, In firebug window
click on element selector (i.e. arrow on firebug option tab)

Now click on message text, you will see a div element which have this "data-sigil='message-text'" attribute.

This div have data attribute which is named as data- store and you are done.
This data have a property
"author":100001xxxxxxxxx where this value is the author id mean page admin id. (i.e. 100001xxxxxxxxx)

To get the name of the author's profile ID which is 100001xxxxxxxxxx
Just copy the number and post it into your timeline box
just like this => @[[100001xxxxxxxx:0]]
then click post.
Automatically, the author name will appear

Note: If that page is managed by many admins, it will show the writer of that post (not main administrator)

Try In Your Luck..