How do I add add a wet signature manually on a tablet?

Hi all,

I've created a form to track some construction work in various properties but I am struggling with one feature. The completed form will be used by a colleague to collect information and capture signatures on a tablet. I need an option to activate a text or signature field so it expands the field into a space large enough for individuals to sign using their finger or a stylus on a tablet screen. The signature  doesn't have to seal the document, or digitally authorise the form, I just need to capture a 'wet' signature. I'd prefer to achieve this without using any additional software if possible.

Many thanks in advance,

John