Please note that when you enable ‘login with service’ for the first time, you will be prompted to test it with your own social network details (e.g. your Facebook account). Your test login will have no effect on the user mode.
Enabled option will then look like this in the sign in/sign up form:
This is an example of sharing widgets on a site page:
Go to System > Social networks > Pages (/admin/social_networking/pages/) to select the widgets types and the pages they will be used on:
Click ‘Widgets’ and you will get to activate different available types of widgets on selected page: