Question: I took a bunch of screenshots and I want to make them pages in a single PDF. Selecting all four in Preview and exporting to PDF only exports two (?), separately. The "Export to PDF" File menu function adds a strange white border around the screenshots (and orients the page as portrait). So I converted each to PDFs individually and then combined them manually. I tried the solutions [here](https://apple.stackexchange.com/q/11163/21351), but Mavericks' Preview doesn't appear to work that way anymore. What's the best, free, hopefully built-in way to automate this?

Answer: 
You can use the `convert` command if you install **ImageMagick**. ImageMagick isn't always a simple install, but if you install Xcode and [Homebrew](http://brew.sh) it should be fairly painless.

`convert *.png foobar.pdf`

<http://www.imagemagick.org/script/convert.php>
There is an Automator action - **New PDF from images**. It creates a single multi-page document from input images. You can create a workflow or app that would process your images that you drop onto it.

If I create an application in Automator with that single action, I can drop my images onto it, and it'll create a PDF with one page per image.