What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
The radio button field is actually designed to only allow your user to select one option.
If you need to select more than one options, then I believe what you need to use is the check box field.
Here's a quick tutorial about it:
1. Add the check box field under the "Basic Fields" section. You can also enabled the "Allow Other" option here.
2. If you explore the properties of it, you can see that it allows you to set the minimum and maximum number of selections that your users can choose:
I hope that helps.