I'M USEING THE SIM API, WHEN THE HOSTED PAYMENT FORM COMES UP THERE IS A SET AMOUNT PLACED ON THE FORM. I WANT MY CUSTOMERS TO BE ABL TO ENTER THE AMOUNT THEY WANT TO PAY AT THAT TIME. HOW CAN THIS BE DONE?
When you use the hosted payment form you must have the end-user specify the amount prior to transferring them to the Authorize.Net hosted payment form, as the fingerprint which is generated in your SIM code and which allows a successful transfer to the hosted payment form requires an amount to have been specified for calculation of the fingerprint value. You can place a simple page on your server where the customer can specify this amount for this calculation if you'd like. A simple HTML example of this is:
<form method="post" action="simphp.php">
<!-- END HTML PAGE -->
You will also need to make adjustments to you SIM code file to expect and use the amount included in the POST.