Convertkit subscription through API Subscription

Convertkit subscription through API -

function handle_custom_registration_complete_event($member_data,$custom_fields)
{
//print_r($member_data);
$param= array();
$param['api_key'] = 'U7MAIGT9J4LF51bm_kP3Og';
$param['name'] = $user = $member_data['user_name'];
  $param['email'] = $email = $member_data['email'];
$url = 'https://api.convertkit.com/v3/forms/32338/subscribe';

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: application/json'));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($param));
$results = curl_exec($ch);
curl_close($ch);
//print_r(json_decode($results));
if(isset($results->subscription->id) && $results->subscription->id>0){

}else{
}
}