The checklist example SmartList shows a working example of how to use the checklist plugin.  The checklist plugin must be installed to use this example properly.

Create a new record in this SmartList, then tap on the button labeled "My checklist".  Select one or more of the items in the checklist, then tap "Return to SmartList To Go".  Now, open the memo field for the results to see which items were selected.

Add more items, or view the properties of the checklist plugin in the Field Designer to see how this was created.