As you may have heard, we have had to disable the services that were providing social and share-this-page functionality for us (See GDPR, Jetpack, and your devcenter). Currently we do not have a site- or theme-wide way to do this.
BUT…The IBM web design system we support in our sites, V18, has a simple, per-page solution that I’ve made an example of in one of our devcenter blogs:
See that at the bottom of that page, there are now (IBM, default) share icons:
And that the code for this is just a one-liner you can put anywhere you want:
See more on this page: http://northstarexamples.mybluemix.net/v18/elements/sharethispage/