I find "electronic signature" to be a very strange thing. Since it's not really the person's signature, and since the recipient doesn't know what he should be getting, how is not easily forgeable?
I scanned my actual signature, which at least looks like my other signatures, if they've seen one.
And with other free software, I can paste into a pdf file or, I'm sure, anything that takes graphics. And the one time I did this, the recipient was satisfied.