Hello Linux Geeksters. As the name suggests, Document Viewer App is the default document viewer application created for Ubuntu Touch, being part of the Core apps package and running on Ubuntu SDK.
The support for PDF files was added recently, but it will be updated until the release of Ubuntu Touch. Among other features, when resizing the app while reading PDF files, the PDF page adapts to the screen, this being good for both monitors and phone screens
To install and test Document Viewer App on Ubuntu 13.10 Saucy Salamander, do the following:
$ sudo add-apt-repository ppa:ubuntu-sdk-team/ppa
$ sudo add-apt-repository ppa:ubuntu-touch-coreapps-drivers/daily
$ sudo apt-get update
$ sudo apt-get install ubuntu-sdk ubuntu-docviewer-app