You can add your electronic signature to your Google Docs document in several ways. The first method involves using the Google Doc built-in drawing feature, which allows you to hand draw a signature and insert it into your document. You can also upload an image of your signature. The easier method involves using Signaturely, a web-based digital signature software. All you need to do is log in to your free Signaturely account and sync it with your Google Drive. Then you can upload your document file and use the Signaturely editor to sign it digitally.