Signing a spreadsheet

[jsambrook]

I want to be able to have a user sign the spreadsheet. Is there anyway I could do this other than uploading an image of the signature? Is there an electronic signature? I've googled it but nothing seems appropriate.
thanks

 

[baitmaster]

If I need someone to approve something in a spreadsheet, I get them to email it, that way its fixed in both their outbox and my inbox

I dont know anyway that they can "sign" a sheet, that I can't easily fake