How to import fillable PDF form.

If that fillable PDF form was from Adobe FormsCentral, it will be possible as shown on this guide: https://www.jotform.com/help/340-How-to-Import-Adobe-FormsCentral-PDF-Forms-to-JotForm 

Otherwise, it wont work. However, you can create a webform from the scratch using our builder, and then export it to a fillable PDF form if you want to: https://www.jotform.com/help/312-JotForm-Fillable-PDF-Creator-with-All-Points 

Let us know if you need more help, we will be glad to assist you.