Lets say you have an input box where you enter something that you want to share to your timeline. Can you have a checkbox beside an ADD Button that will specify that you want to share explicitly to your timeline? Is this against Facebook policy?
Eg. I want to go to ______________ ADD CheckBox Automatically checked.
That's fine. The purpose of Explicitly shared simply means that the user is being made aware that the post will go to their Facebook Timeline. For things like "reading an article" which happens automatically, that can't be explicit, because the user isn't approving it.
If you add a checkbox to post to Facebook (and implement the code to do so), it can definitely be an explicit post.