acf creating-a-front-end-form/
<?php acf_form_head(); ?>
<?php get_header(); ?>
<div id="primary">
<div id="content" role="main">
<?php /* The loop */ ?>
<?php while ( have_posts() ) : the_post(); ?>
<h1><?php the_title(); ?></h1>
<?php the_content(); ?>
<p>My custom field: <?php the_field('my_custom_field'); ?></p>
<?php acf_form(); ?>
<?php endwhile; ?>
</div><!-- #content -->
</div><!-- #primary -->
<?php get_footer(); ?>