E-signature for documents

I have a question about the signature component.
For my app i want carpenters to be able to let their clients sign a document or offer in person with a e-signature. How would i integrate this feature?

My first thoughts are you either have to use something like Docusign to let the client e-sign the document (and save the signature as a part of the document), or add the signature component inside the app, and generate a new PDF using PDFMonkey/DocsAutomator.