The Reality Check tool simulates the model in order to test the Reality Check that is currently selected into the Workbench. If you do not have a Reality Check selected into the workbench, you will receive an error message.
The run name used will be that shown in the top toolbar — you will not be asked if you want to overwrite this run even if it exists. This analysis tool is equivalent to choosing one Reality Check in the Reality Check Control dialog (see Chapter 14 of the User Guide) and pressing the button Highlighted to run that check.