After the round is completed, go to the strokes screen for the hole, create the additional stroke, record what happened, tap on maps, and place your finger with a long press on the location and hit Save.
As there could be one, two or three additional strokes, these additional strokes will create duplicate stroke numbers. As a result, warnings on the stroke list screen indicating, Warning: Check your stroke numbers will appear.
Review your list of strokes, identify the duplicated numbers, work out how many strokes you had on the hole and re-number each stroke from the last stroke, going back to the point where the additional strokes were entered.
Save each stroke with its new stroke number and remember to remove the penalty number.