iAnnotate PDF: Highlight, Mark Up, Sign
PDF (portable document format) is an Adobe-owned file format commonly used for distributing static, formatted documents with others. While a variety of free PDF “viewer” applications are available for different computer platforms, commercial software is generally required to highlight, mark up, and even “sign” PDF files so those annotations are viewable by others. iAnnotate PDF ($10) is an excellent application which not only permits users to highlight PDF files, but also add typed comments as well as signatures.
Check out this 6.5 minute video tutorial for instructions about using iAnnotate PDF to sign PDF documents.