With ValidSign it is possible to require text fields. It is not possible to sign a document without filling in required fields. This allows you to force signers to fill in fields. Below is described how you can require fields.
After you have added the signers and documents to the transaction, you will be redirected to the 'Designer'. This screen is shown below
Signature fields are by definition required and therefore do not need to be explicitly required. After you have dragged all fields (text field, list, radio button, etc.) into the document, you can indicate which fields you want to require. Place your mouse on the field and click on the gear to the right of the field.
The pop-up below will now be shown. Click on the 'Slider' circled with a red color. Then click save.