Use the "Additional date" section to add instances to the Entry that do not fall within the pattern of recurrences you chose. Note: If you add additional dates and click List dates afterwards, your additional dates will be erased.
Dates for the Entry are listed at the bottom of the dialog box. By default, any changes you make to the Entry (e.g. adding or deleting invitees, modifying the title) will apply only to the dates selected in the list box.