Problem is the plugin only supports some limited predefined fields: first name, last name, lead source, title, company, email, phone, street, city, state and zip.
We would like to submit to salesforce some rsform custom fields as well, and this actually seems to be possible and not so hard, given the provided "web2lead" and "silent post" tools available.
But i just cant figure out how to addapt the provided "web2lead" SF custom provided form, to a "Script called after form has been processes" in order to Silent Post to SalesForce the provided form data