wkhtmltopdf: What paper sizes are valid?
If you take a look through the pdfsettings.cc source in the project repository, you'll find this list, which looks to me like the accepted list of named paper sizes.
res["A0"] = QPrinter::A0;res["A1"] = QPrinter::A1;res["A2"] = QPrinter::A2;res["A3"] = QPrinter::A3;res["A4"] = QPrinter::A4;res["A5"] = QPrinter::A5;res["A6"] = QPrinter::A6;res["A7"] = QPrinter::A7;res["A8"] = QPrinter::A8;res["A9"] = QPrinter::A9;res["B0"] = QPrinter::B0;res["B1"] = QPrinter::B1;res["B10"] = QPrinter::B10;res["B2"] = QPrinter::B2;res["B3"] = QPrinter::B3;res["B4"] = QPrinter::B4;res["B5"] = QPrinter::B5;res["B6"] = QPrinter::B6;res["B7"] = QPrinter::B7;res["B8"] = QPrinter::B8;res["B9"] = QPrinter::B9;res["C5E"] = QPrinter::C5E;res["Comm10E"] = QPrinter::Comm10E;res["DLE"] = QPrinter::DLE;res["Executive"] = QPrinter::Executive;res["Folio"] = QPrinter::Folio;res["Ledger"] = QPrinter::Ledger;res["Legal"] = QPrinter::Legal;res["Letter"] = QPrinter::Letter;res["Tabloid"] = QPrinter::Tabloid;