$ sudo apt-get update
$ sudo apt-get install rsyslog-relp 

rsyslog-relp is installed in your system.

Make ensure the rsyslog-relp package were installed using the commands given below,

$ sudo dpkg-query -l | grep rsyslog-relp *

You will get with rsyslog-relp package name, version, architecture and description in a table

rsyslog-relp package basic information: