Install agent following Puppetlabs howto

Add the line server = foreman.rmlab to the "agent" section of puppet agent conf file (/etc/puppet/puppet.conf)

Run puppet agent --test

If the host domain is different from ".rmlab" you have to accept the connection to the puppet master: go to Foreman Web UI → Infrastructure → Smart Proxy → Certificates and enable agent hostname

Assign node from Foreman Web UI to an host group or config group

Run puppet agent --test to apply first configuration