If you require a file using a URL, it's going to give you the generated results rather than the PHP source, unless you have an htaccess directive telling it to treat .php as plaintext or something (which would be very bad for security). So this line is going to create problems. You need the SDK stored locally on the site's hosting so you can reference it locally.
<?php require_once 'http://www.koraminsurance.com/temp/anet_php_sdk/AuthorizeNet.php'; // The SDK
Your relay response page also generates a syntax error. Whether it does that when called properly, I don't know, but that might need to be checked into as well.
$relay_response_url = "http://www.koraminsurance.com/temp/relay_response.php"; // You will create this file in See Create relay_response.php...
Also, are you running this on a sandbox account or a production account? The function call needs an additional argument if you're running it on production. From the AuthorizeNetDPM.php file in the lib folder of the PHP SDK:
public static function getCreditCardForm($amount, $fp_sequence, $relay_response_url, $api_login_id, $transaction_key, $test_mode = true, $prefill = true)
Might also help if you can tell me exactly what happens when you try to fill this out.