HTTP Request2
require_once 'HTTP/Request2.php';
$request = new HTTP_Request2();
$request->setUrl('https://api2.archery-records.net/api/members');
$request->setMethod(HTTP_Request2::METHOD_GET);
$request->setConfig(array(
  'follow_redirects' => TRUE
));
$request->setHeader(array(
  'Authorization' => '<API-KEY>'
));
$request->setBody('');
try {
  $response = $request->send();
  if ($response->getStatus() == 200) {
    echo $response->getBody();
  }
  else {
    echo 'Unexpected HTTP status: ' . $response->getStatus() . ' ' .
    $response->getReasonPhrase();
  }
}
catch(HTTP_Request2_Exception $e) {
  echo 'Error: ' . $e->getMessage();
}
cURL
$curl = curl_init();
curl_setopt_array($curl, array(
  CURLOPT_URL => 'api2.archery-records.net/api/members',
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => '',
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 0,
  CURLOPT_FOLLOWLOCATION => true,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => 'GET',
  CURLOPT_HTTPHEADER => array(
    'Authorization: <API KEY>'
  ),
));
$response = curl_exec($curl);
curl_close($curl);
echo $response;
Guzzle
$client = new Client();
$headers = [
  'Authorization' => '<API KEY>'
];
$body = '';
$request = new Request('GET', 'https://api2.archery-records.net/api/members', $headers, $body);
$res = $client->sendAsync($request)->wait();
echo $res->getBody();