$ sudo apt-get update
$ sudo apt-get install rsplib-registrar 

rsplib-registrar is installed in your system.

Make ensure the rsplib-registrar package were installed using the commands given below,

$ sudo dpkg-query -l | grep rsplib-registrar *

You will get with rsplib-registrar package name, version, architecture and description in a table

rsplib-registrar package basic information: