ReaddleDocs (documents/attachments viewer and file manager) PDF Expert - Fill forms, annotate PDFs for iPad on the iTunes App Store. Notability - Take Notes & Annotate PDFs with Dropbox Sync. iAnnotate PDF for iPad. Remarks - Write notes and Annotate PDFs. GoodReader for iPad. DocuSign Ink for iPhone 3GS, iPhone 4, iPhone 4S, iPod touch (3rd generation), iPod touch (4th generation) and iPad on the iTunes App Store.