Apple Preview has a built in feature that allows you to create great electronic signatures in PDF documents. Combine this with a cloud based storage platform and you can have a paperless office in no time. Each time you sign a PDF document in preview the file is automatically saved. When the file is saved, Google Drive will sync this document to your cloud storage. Share this file with others, and they have instant access to the file and are able to add signatures and edits of their own.