With PDF annotation, files can be modified with shapes, arrows, and text. Important passages can be highlighted and instructions can be added, which makes Skitch an even better collaboration tool. PDFs are sent with a summary of all annotations.
The new version supports Stamps, which are designed to offer fast feedback. For example, Stamps can be placed to indicate whether something is liked, disliked, or unclear in a document. Skitch has also added a plain text notation mode and a Tool Tip to explain the new features.
While all Evernote users will receive 30 days of access to PDF annotations, continuing to use the service will require a premium membership. Skitch is free to use, but a premium membership costs $5.00 per month or $45.00 per year.
Skitch for Mac [Direct Link]
Skitch for iOS [Direct Link]