$ sudo apt-get update
$ sudo apt-get install root-system-proofd 

root-system-proofd is installed in your system.

Make ensure the root-system-proofd package were installed using the commands given below,

$ sudo dpkg-query -l | grep root-system-proofd *

You will get with root-system-proofd package name, version, architecture and description in a table

root-system-proofd package basic information: