ResBook doesn't just have the ability to include services in your bookings, but you can also create Add-On's. Add-On's differ from services in the sense that Add-On's allow for images to be added to them, and can be used to differentiate things like Breakfast etc. from things like Airport Transfers.
To create Add-ons, simply go to:
ResBook > Settings > Stock Configurations > Services > (Click on Service Name) > (Click on "Addon" Tab). (image1.0)
If you click on this slider, then the selected service will then become an Add-on (image 1.1). A test link will appear beside the button. This link will take you to the photo gallery for you to upload pictures of the Add-on.
Upload images, and you will have created your Add-on. You can access these images from the Photo Gallery if you want to remove or change images.