To set up a Security Bond in ResBook, you will need to create it as a service.
Go to Settings > Stock Configurations > Services.
Name the service "Security Bond" and make sure you set the Pricing Model to "Per Booking". The remaining settings are at your discretion.
Once you have finished, click "Add".
Once created, click on the service and then click the "Settings" tab.
Ensure that the "Bond" check box is ticked. Hit the "Save" button, and your Security Bond will be created.