my_pmprorh_init.php

<?php

function my_pmprorh_init()
{
	//don't break if Register Helper is not loaded
	if(!function_exists( 'pmprorh_add_registration_field' )) {
		return false;
	}
	$fields = array();
	$fields[] = new PMProRH_Field(
		'horseriding_type', //
		'text', // type of field
		array(
			'label'     => 'TYPE of HORSERIDING DISCIPLINE:', // custom field label
			'required'  => true, // make this field required
			'profile'   => true, // show in user profile
			'memberslistcsv' => true, // Uncomment to Include in Member List CSV Export
			// 'addmember' => true, // Uncomment to display in Add Member
		)
	);

	$fields[] = new PMProRH_Field(
		'horse_breed', //
		'text', // type of field
		array(
			'label'     => 'BREED OF HORSE:', // custom field label
			'required'  => true, // make this field required
			'profile'   => true, // show in user profile
			'memberslistcsv' => true, // Uncomment to Include in Member List CSV Export
			// 'addmember' => true, // Uncomment to display in Add Member
		)
	);

	$fields[] = new PMProRH_Field(
		'hoese_size', //
		'text', // type of field
		array(
			'label'     => 'SIZE OF HORSE:', // custom field label
			'required'  => true, // make this field required
			'profile'   => true, // show in user profile
			'memberslistcsv' => true, // Uncomment to Include in Member List CSV Export
			// 'addmember' => true, // Uncomment to display in Add Member
		)
	);

	$fields[] = new PMProRH_Field(
		'hoese_color', //
		'text', // type of field
		array(
			'label'     => 'PREFERRED COLORS FOR YOUR HORSE:', // custom field label
			'required'  => true, // make this field required
			'profile'   => true, // show in user profile
			'memberslistcsv' => true, // Uncomment to Include in Member List CSV Export
			// 'addmember' => true, // Uncomment to display in Add Member
		)
	);

		$fields[] = new PMProRH_Field(
		'your_color', //
		'text', // type of field
		array(
			'label'     => 'PREFERRED COLORS FOR YOURSELF:', // custom field label
			'required'  => true, // make this field required
			'profile'   => true, // show in user profile
			'memberslistcsv' => true, // Uncomment to Include in Member List CSV Export
			// 'addmember' => true, // Uncomment to display in Add Member
		)
	);


	//add the fields into a new checkout_boxes are of the checkout page
	foreach($fields as $field)
		pmprorh_add_registration_field(
			'checkout_boxes',				// location on checkout page
			$field						// PMProRH_Field object
		);
	//that's it. see the PMPro Register Helper readme for more information and examples.
}
add_action( 'init', 'my_pmprorh_init' );