To create this kind of button you have to:
- Copy the URL address of your landing page,
- Go to Facebook Like Button Configurator, click Like Button Configurator and paste the landing page web address to URL gap,
- Choose the button type and its settings,
- Click "Get code" and copy the first one (skip a part of <div>..</div>),
- Go back to the Facebook Configurator and copy the second part of the code,
- Now, move to the editor of your landing and drop the element "Custom HTML" on the page.
Open the element and add the code. Publish your landing page and see how the button displays and if it works properly. You can always go back to the editor and move the button around, to some other place of a landing page.