All you gotta do is just download the customized setup file and then use the built in installation wizard to extract the content to a folder. Now you can just copy this folder to any portable media that you have (say to a USB pen/HDD, etc or can use the setup wizard to do that automatically for you as well) and switch it to a different computer (only supports MS Windows) and simply launch the Foxit reader from there!.
Another benefit of having a portable reader such as this is, all the changes that you make to the application (preferences, etc) are saved within its extracted folder thus are also applied when you launch it in a different computer thus you don't have to make all the changes manually either.
*. 9MB of downloading size (about 34MB when extracted).
*. Includes all the features of the original Foxit reader: Viewing PDF files, search/find text, add-comments, highlight text, tool-bars, etc... they're all there.
*. Launches without modifying any installed software and does not add any registry entries (other than the ones that MS Windows creates automatically).
*. Optimized for the USB drives.
If interested, you can get it from this downloading page and once the downloading completes, just follow the on screen instructions to extract it to a desired location. As soon as Foxit developers release a new version, the portable app developers also make sure to update their database thus make sure to visit their link to check for the updates too.