If you have a PHP page hosted on a web server you can call it from a web viewer or Insert From URL script step. You can use httppost:// to send a post request in filemaker to a PHP page with the Insert From URL script step. e.g. httppost://localhost/test.php?name=bob
In this example your $_POST array in your PHP page will have the index "name" = "bob"
Another option is use the Send Event script step to run php.exe to parse a specified PHP file however I don't think you can view the result of the execution with Send Event. e.g. php.exe -f "C:/inetpub/wwwroot/test.php". Here's a full list of command line arguments http://php.net/manual/en/features.commandline.options.php.
Thanks for the reply, very helpful! You have taught me about two things to research more about. I will test to see what is possible. Thanks