Signature with date stamp

I am working on the Adobe Acrobat Pro 9 platform.

I have a PDF form that needs to be signed by multiple people on their phones. How can I add a signature field, where they can sign with their finger or phone's stylus? Other people will have the free Adobe Acrobat apps on their phone.

Also, is there any way to have the signature date/time stamped? So, I imagine that once a person signs the form, the date and time are automatically stamped next to the signature. It would be a good way to ensure that the form is signed when it should be signed.

I'm a beginner at this, so step-by-step instructions or a video would be super helpful. 🙂