Skim for Mac
The Apple vetted Preview application that comes as a built utility within Mac OS X is able to open PDF documents and even includes basic annotation tools: you can underline text, add text boxes, thoughts bubbles, and so on.
Skim is an open source project that includes all these basic PDF management functions, but also offers support for working with AppleScript, Apple Remote Control, LaTeX, SyncTeX, BibDesk, and more.
Streamlined PDF viewer and annotator that features an intuitive interface
The Skim main window is visible only when working on a document, so you must start by opening a PDF file. Skim allows you to quickly navigate the file by viewing the pages thumbnails or the table of contents, while the center area is reserved for visualizing the PDF content. At the same time, Skim features a third panel that displays your notes in list mode.
For your convenience, the top area of the Skim main window provides both navigation buttons and annotation tools: their icons and names are mostly self-explanatory (hoover your mouse on top of each icon to see the tool name).
Seamlessly synchronize modifications within the PDF document with the TeX source file
Via the Skim Preferences window you can adjust general details concerning the app’s look, such as the display appearance or the default note colors. Most importantly, in the Sync panel, you can easily enable the “Check for file changes” function and choose a PDF-TeX Sync preset.
Skim offers you the possibility to synchronize the source TeX file with the PDF document, as long as both Skim and the TeX editor know about one another. By default, Skim is able to work with popular TeX editors, such as TextMate, BBEdit, LyX, TeXMaker or MacVim, but you can also create your own custom presets.
Versatile solution for viewing and annotating PDF documents, while synchronizing them with the source TeX file
Skim proposes a clean and organized environment for performing basic PDF annotation tasks: the app’s main window provides quick access to most tools, and you can find your way around without too much trouble.
Noteworthy is that Skim also comes with a PDF-TeX Sync function, and that you are able to visualize the source TeX code corresponding to a certain line in the PDF document.