You can upload a picture of your signature in Sleek Bill Online by going to your Dashboard - Preferences - General (https://app.sleekbill.in/settings/general)

Towards the end of the page you can see the upload signature section. Please follow the instructions and then click on save.

After you have uploaded your signature, please go to Preferences - Documents: Invoices (https://app.sleekbill.in/settings/documents/invoices) and make sure you activate "Show Primary Signature", then save.

You can activate the signature for Quotes, Delivery Notes, Credit Notes and Purchase Orders in a similar way.