Yes, as noted on your website admin panel Configure Site > Social Networking > Timeline configurations page, in the "Include Share Button for" section, on your Timeline page (on the add/edit page, where you have copy/pasted the Timeline Placeholder Text), you need to scroll down to the "Include Shares On Page" section, and turn it on to use this feature on your Timeline. Choose either "Yes" or "Yes, with Add Comment Option". On the Timeline configurations page, you can choose which apps to activate the share button for, i.e. for photo uploads, video uploads, listings, classifieds, etc.