i have this drama all the time when i'm sending pdfs to suppliers with older RIPs (i.e. they can't take my imposed file from my RIP which contains my spot colours such as diecut, score, spot uv varnish, foil, emboss, etc). its a nusiance and i wish they'd upgrade their RIPs, but until that time this is what i do:
1) take the pdf into indesign. if its one page just go file, place. if its several pages or an entire book worth of spot varnishes, use the multipageimporter2.2.1 which is available from https://creativepro.com…..downloads/
2) go file, print. prepare the appropriate page size and marks as normal, but make sure that the file is prepared as separations and only select the separation you want to send the supplier. i normally print to a ps file and then distill this with acrobat distiller.
this is normally all i need to do BUT if i get a supplier who THEN says “all text has to be converted to curves” (man i hate it when they ask that – grrr), THEN i take the pdf into illustrator and convert all text to paths and save out as an eps.
IMHO this is a nusiance because each time i have to take additional steps in preparing for these suppliers' draconian specs, i stand a very good chance of destroying the digital integrity of the file, and make it more likely to accidentally foul up the artwork. i put it this way: any supplier which CAN accept files which DON'T have to be set up as black/converted to curves etc… will receive more of our business.