There is another dead simple way to do this without an options page (but using an option page for items displayed throughout the site, like footer info, can provide a more logical place for clients to enter things).
Here is an example of a field displaying a newsletter link on the homepage:
<?php the_field( 'newsletter'); ?>
Here is the same code but modified to display in the side bar of all other pages of the site:
<?php the_field( 'newsletter', 2 ); ?>
The “2” is the post ID of the homepage – that’s it!
FYI this is hardcoded into my custom theme files.
