Below is an example of making an HTTP request to cron.roflcopter.fr from PHP.
file_get_contents('https://cron.roflcopter.fr/ping/your-uuid-here');
If you would like to setup timeout and retry options, as discussed in the reliability tips section, there is a curl package available that lets you do that easily:
use Curl\Curl;
$curl = new Curl();
$curl->setRetry(20);
$curl->setTimeout(5);
$curl->get('https://cron.roflcopter.fr/ping/your-uuid-here');
Note: this code does not throw any exceptions.