Solved! Go to Solution.
To add to this:
If you plan on using this field in your CRM, which it sounds like you are, I would recommend creating the field in your CRM and letting it sync over to Marketo. In SFDC, this is Setup>Customize>Leads>Fields>New.
Also,
If you do not create the field in SFDC first, it will never be available in SFDC. You can still populate the value in alerts to sales but the info will not live on the record in SFDC layouts, reports, or views.
Justin
Hey Matt, I moved your question to the Products & Support category for more visibility.