Hi Ravish,
Thank you for contacting Syncfusion support.
We have support for Hand-Written signature in our PDF Viewer. The size of the signature field depends on the size provided in the PDF document. If you need to increase the size of the form fields it should be done at the time of document creation, we can’t dynamically increase the size of the form fields.
Please let us know if you have any concerns on this.
Regards,
Akshaya