Hello,
At this moment we do not have this functionality in Muse Form.
I would suggest you to go to the link below and voe for this idea.
https://forums.adobe.com/ideas/2329
As this point I would suggest you to create a form of your requirement at http://www.jotform.com/.
Once the form is created, generate the embedded code for the form and place it in Muse by Object > Insert HTML.
Regards
Vivek