How to Open PDF Files on a Mac
Preview is the default program for viewing PDF files in a Macintosh operating system, and will automatically open the file unless you have specified a different program to do it. If you have preset your computer to use other programs to open a particular PDF, you can override that. Preview opens quickly and provides easy access to the document, though without some of the PDF editing options that other programs (such as Adobe Acrobat) provide.
Navigate on your computer to the location of the PDF file and click on the file to highlight it.
Press the "Command" and "I" key simultaneously (the "Command" key has an insignia of a square with loops on the corners.) This is the "Get Info" command, and can be used to find out the characteristics of a file, as well as to direct which program to use to open a file.
Click on the dropdown arrow under the "Open With" section, and scroll down until you see "Preview." Click on "Preview" to select it.
Close the "Get Info" window.
Double-click on the PDF file. It will open in "Preview."