Esc Key will exit from the current screen or box and take you to the previous screen. From the Main Menu the Esc key will bring up the Exit Program dialog box which exits RTO Pro. You can use the ESC key to cancel any transaction in processing up until the time you push ENTER on the "Tendered" screen to print a receipt.
Tab Key is used to go from one field to another. You can also do a reverse Tab by holding down SHIFT and pushing Tab. The tab key is the preferred method to go from field to field when you are entering in info, when the page is finished you generally push ENTER to go to the next page.
ENTER Key is generally used to go from one page to the next, you push Enter when all fields are filled in and you are ready to proceed to the next screen.
Arrow Keys can be used on list screens to move through the list and can also be used to switch focus from field to field on most screens.
F1 will bring up the RTO Pro Help file from just about anywhere, most screen have context sensitive help so the help topic that displays will be the topic for the screen you are on.
F2 will bring you to the Payment Screen from just about anywhere.
F5 is generally used to start reports.
F6 is generally used to complete transactions, or take you to the tendered screen where you enter the payment form (cash, check etc.), then push Enter to complete..
When your not sure how to do something look around at the buttons that are available. Below is from the payment screen, as you can see there are lost of buttons at the top. You can hover over the buttons and a longer description of what they do will display like it shows below for the "F8" button on the payment screen.