http://www.digisigner.com/ can be used in the free version to sign your pdf. Better and stupid simple (this is a good thing): https://www.buergerkarte.at/pdf-as/ they claim that you could use the onlineservice with many smartcards from europe.... dont know if this is right but i tested it with my austrian insurance card (e-card). the domain buergerkarte.at is hosted by the technical university graz (see nic.at) and therfore it should be quite save to trust the hoster but keep in mind that technicaly the hoster of this service has access to your document.