$ sudo apt-get update
$ sudo apt-get install razorqt-appswitcher 

razorqt-appswitcher is installed in your system.

Make ensure the razorqt-appswitcher package were installed using the commands given below,

$ sudo dpkg-query -l | grep razorqt-appswitcher *

You will get with razorqt-appswitcher package name, version, architecture and description in a table

razorqt-appswitcher package basic information: