How to had pdf output format to several pages

Hi, I’m looking a way to publish pages as html and pdf. I m trying with output format. for the moment i have this message when generating the site :
" WARN found no layout file for "pdf" for kind "page": You should create a template file which matches Hugo Layouts Lookup Rules for this combination"
Do I have tu put an specific single file in layouts ?
Has anyone already implemented such a feature and could help me?

See this post, always good to do a search before posting.