It shall be unlawful for an employing person to knowingly, directly or indirectly, enter into an agreement to recruit or solicit foreign guest workers with a foreign labor contractor who has not registered with the Labor Commissioner pursuant to the regulations set forth in this subchapter. Knowledge may be established where the employing person (employer) has actual knowledge that the contractor is not registered or where the person should have known that the contractor was not registered under particular circumstances which includes, but is not limited to, a failure by the person or employee of the person to reasonably exercise due diligence in view of the contractor registration requirement and the prohibited use of an unregistered contractor.