In fact it is not hard to add a "Facebook like" to his site
- Register as a Facebook Developer
- Add your site as an application site
- add the javascript+html script piece that goes well by updating the application identifier 'xxxxx'
For example to add a like insert the following code:
facebook.js file
window.fbAsyncInit = function() { FB.init({ appId : 'xxxxx', xfbml : true, version : 'v2.6' }); }; (function(d, s, id){ var js, fjs = d.getElementsByTagName(s)[0]; if (d.getElementById(id)) {return;} js = d.createElement(s); js.id = id; js.src = "//connect.facebook.net/fr_FR/sdk.js"; fjs.parentNode.insertBefore(js, fjs); }(document, 'script', 'facebook-jssdk'));
Article
I have included both parts (html code + javascript ) in a plugin