Markup PDF Pages with Drawings
http://www.planetpdf.com/enterprise/article.asp?ContentID=Markup%5FPDF%5Fpages%5Fwith%5Fdrawings&gid=7547

Shea, Dan
PlanetPDF
2007

Abstract:

Using Acrobat, PDF has been established as a popular and user-friendly medium for collaborative workflows. Not only can you add sticky notes or highlight text, you can even draw polygonal or freehand annotations. This tip explains how.