gistfile1.txt

/*
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'	=> true,
'memberslistcsv'	=> true,
'required'	=> true,
)
);
$fields[] = new PMProRH_Field(
'how_hear_referrer',
'text',
array(
'label'	=> 'Referred by',
'profile'	=> true,
'memberslistcsv'	=> true,
'depends'	=> array(array('id' => 'how_hear', 'value' => 'other'))
)
);
foreach($fields as $field)
pmprorh_add_registration_field( 'additional', $field );
}
}
add_action( 'init', 'my_pmpro_how_hear_fields' );