Adds a Register Helper "My Extra Field" input after billing fields.

sample_pmprorh_init.php

<?php
/**
 * Adds a Register Helper "My Extra Field" input after billing fields.
 */
function sample_pmprorh_init() {
	//don't break if Register Helper is not loaded
	if ( ! function_exists( 'pmprorh_add_registration_field' ) ) {
		return false;
	}
	
	//define the fields
	$fields = array();
	$fields[] = new PMProRH_Field(
		'new_field',
		'text',
		array(
			'label' => 'My Extra Field',
			'profile' => true,
			'required' => true
		)
	);

	//add the fields into a new checkout_boxes are of the checkout page
	foreach ( $fields as $field ) {
		pmprorh_add_registration_field(
			'after_billing_fields',
			$field
		);
	}
}
add_action( 'init', 'sample_pmprorh_init' );