This form is opened from the Database Administration form - Tools - Foreign Key Checker.
Foreign Key Checker
Filter Foreign Keys
Enter a string to filter the results. This string must appear as part of the Primary Key or the Foreign Key for a relationship to be displayed. Use the Internal table relationship 
and User-defined table relationship 
buttons to define which relationships to show.
You can select one or more items in the list (a right-click context menu lets you Check All or Uncheck All) and then press Continue to perform the check on the chosen items.
If any missing foreign keys are found, then you will see this form.