The End with Rejection action is different with the End action. The End action will be the final End point of the workflow, while the End with Rejection is the special case for workflow ending.
So the End with rejection action should be only configured as the End after an assignment task is rejected. Once the workflow is end with rejection, the workflow is end and the form can be re-submitted again by the form owner.
A sample of the configuration for Assignment Task action and End with Rejection action is as below.
To configure the End with Rejection action, lick the "Settings" button under the selected End action.
Enable Email - Turn this ON, if you want to send an email notification after the assignment task is rejected. Yeeflow will include the sample content for the email information, while you can change the setting per your needs.