Your signature appears in the inspector section of every report. Add it once under Settings → Account → Signature.

On the Draw tab, sign directly on the canvas with your mouse, trackpad, or finger (it works on touch devices). Use Clear to start over, then Save Signature to upload it. The save button activates once you've drawn something.
Prefer to upload? Switch to the Upload Image tab, click Choose File, and pick an image of your signature. Images must be under 512 KB and are resized to a max of 800px.
Once saved, your current signature shows at the top of the page for reference, and it's placed in the inspector section of your published reports. To replace it, just draw or upload a new one.