Click on the Edit link for the Survey.
Under the Edit tab click on the "Security" link under Survey Control.
Select the SSL option under Security and Save the Changes.
No - The SSL Certificate is only issued to us. If the SSL Option CANNOT BE COMBINED with a Custom URL. Both these options are MUTUALY EXCLUSIVE. So, for example if you want to use the SSL option, you cannot use the Custom URL and if you want to use the Custom URL option then you cannot use the SSL option.
Note: This is a technical limitation based on DNS and SSL. There is nothing SurveyAnalytics can do solve this issue.