The main content of the Supplement consists of 15 pages of notes and annotations for the complete story, a bibliography, a cover sketchbook, a handful of interviews, some RO Christmas cards, character genealogy, and more. For this digital release I've added in a few extra-extras, namely some more Christmas designs, a previously unavailable (at least publicly) interview, and a little extra artwork. The original Supplement was 48 pages, this one stands at 54. None of this repeats the extras collected at the back of The Complete Rainbow Orchid.
Out of interest, the RO Supplement did see a French translation of a kind - if you purchase the three-volume set of L'Orchidée Arc-en-ciel from BD Must then you also get Le Dossier, a smaller (16-page) edition of the Supplement, featuring three truncated/edited interviews and some different artwork (largely in colour - my English edition is in black and white). There are two versions - a brown 'Collector's edition', and a blue 'Press edition' - both with the same content.
To download the free (English language) Supplement PDF, visit the shop, scroll down to The Rainbow Orchid Supplement and you'll see the link there. Enjoy!