my_pmpro_how_hear_field.php

/*
	Add a "How did you hear about us?" field Membership Checkout for new members only.
	Display the field for admins-only in the profile and in the Members List CSV export.
*/
function my_pmpro_how_hear_fields() {
	global $current_user;
	if(class_exists( 'PMProRH_Field' ) && (!pmpro_hasMembershipLevel() || current_user_can( 'edit_users' ) ) ) {
		
		pmprorh_add_checkout_box( 'additional', 'Additional Information' );
		
		$fields = array();
		
		//how_hear field
		$fields[] = new PMProRH_Field(
			'how_hear', 
			'select',
			array(
				'label'			=> 'How did you hear about us?',
				'options'		=> array(
					'facebook'	=> 'Facebook',
					'twitter'	=> 'Twitter',
					'friend'	=> 'Friend',
					'other'		=> 'Other'
				),
				'profile'		=> 'admins',
				'memberslistcsv'	=> true,
				'required'		=> true,
			)
		);
		$fields[] = new PMProRH_Field(
			'how_hear_referrer',
			'text',
			array(
				'label'			=> 'Referred by',
				'profile'		=> 'admins',
				'memberslistcsv'	=> true,
				'depends'		=> array(array('id' => 'how_hear', 'value' => 'other')) 
			)
		);
		foreach($fields as $field)
			pmprorh_add_registration_field( 'additional', $field );
	}
}
add_action( 'init', 'my_pmpro_how_hear_fields' );