Infinite list widget

how can i add radio button as one of the fields?

Unfortunately, the Infinite List widget can only have one input type.

I would suggest using the Configurable List widget instead, that allows you to have multiple and different input types on each column. Please also read this guide on how to use that widget: http://www.jotform.com/help/282-How-to-Set-Up-the-Configurable-List-Widget 

Do let us know if you need more help on this.