To create a PDF portfolio containing multiple file types.

def AddPackage(doc, file, desc)
    files = NameTree.Create(doc.GetSDFDoc, "EmbeddedFiles")
    fs = FileSpec.Create(doc.GetSDFDoc, file, true)
    files.Put(file, file.length, fs.GetSDFObj)
    fs.SetDesc(desc)
    
    collection = doc.GetRoot.FindObj("Collection")
    if collection.nil?
        collection = doc.GetRoot.PutDict("Collection")
    end
    
    # You could here manipulate any entry in the Collection dictionary. 
    # For example, the following line sets the tile mode for initial view mode
    # Please refer to section '2.3.5 Collections' in PDF Reference for details.
    collection.PutName("View", "T")
end
doc = PDFDoc.new
AddPackage(doc, filename, "PDF")
AddPackage(doc, imagename, "Image")

PDF packages (portfolios)
Full code sample which illustrates how to create, extract, and manipulate PDF Packages (also known as PDF Portfolios).