Simply load your profile or click here (In the License and Education section)
Add your S2 and PTR number and save it
It will now show up on your printouts and send outs automatically if you use the System Footer (this is the footer design built-in to all accounts)
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If you are using Custom Footers:
Just go to Settings (or click here)
Go to Footer
Edit the Footer with your new S2 and PTR number and hit Save