You can put contact form which is created by Contact form 7 or Ninja forms plugin on single listing page.
Please refer to the following about how to set up form using these plugins.
Contact form 7 : http://directory-docs.wpjavo.com/contact-form-7/
Ninja Forms : http://directory-docs.wpjavo.com/ninja-form/
Please move to Dashboard >> Javo Directory >> Theme Settings >> Listing and set up Contact Form Settings option.
Please enter only form id(number) you made into Contact Form ID field.