Attention! This is only the supplement that goes with the pattern from the Regency Gown for sizes 18-26, you will need the pattern of the Regency gown to use the supplement.
This is what Sense & Sensebility has to say about the pattern:
If you measure between an 18-26 or a DD cup, you’ll need this supplement in addition to the original Regency Gown pattern. This takes the pattern up from size 18 through 26, since it was not possible to fit all the extra pieces onto the two sheets in the original pattern. Click to view the Regency Gown Pattern Supplement yardage chart.