How can I run a php file using Cron jobs?

From the cPanel, go to Cron jobs, select Standard, and enter (between the quotes) "/usr/bin/php -q /home/USERNAME/public_html/PathToFile" into the Command to run field. You may also want to adjust the settings specifying when to run the cron job. After you finished, click on the SaveCrontab button.

*Note: You will need to replace USERNAME with your user ID and PathToFile with the file name or the rest of the path to the file.