PDFpen 4.5
If you work much with PDF files, you may find that Preview isn't quite powerful enough for your needs. While Preview, especially in 10.6, includes many...
If you work much with PDF files, you may find that Preview isn't quite powerful enough for your needs. While Preview, especially in 10.6, includes many annotation features (circles, lines, comments, etc.), that's about the extent of its powers--you can't easily insert an image into an existing PDF, for example, nor can you modify the text within that PDF.
SmileOnMyMac's PDFpen not only marks up PDFs, but it makes short work of inserting images and even modifying, to some degree, the text within a PDF. It's also got one very unexpected feature, especially in a program with a reasonable $50 price tag.
Work with PDFs
The heart and soul of PDFpen is marking up and modifying PDFs, starting with a full set of PDF markup tools. Just as with Preview (the 10.6 version at least; the 10.5 version was more limited), PDFpen lets you easily add notes, text boxes, links to other pages in the PDF or to external URLs, and various shapes and lines to your PDF.
Going beyond Preview, PDFpen includes comment boxes (which can be turned on and off for ...
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Rob Griffiths, Macworld.com