If you want an actual signature you'd have to do it as an image. That would then have the disadvantage that people could copy that image and use it to apply the signature to all sorts of other documents.
The way to do it so that the text looks a bit like a signature is to use a cursive font to style the text.
I think it's a very bad idea to place you signature on a website, the potential for forgery, fraud or anything else would be seriously increased, they could take your signature and place it on any number of legal documents signing you up for stuff you have no knowledge of (identity fraud), personally I don't know anyone who would freely give out something as sensitive as their signature on the web. My advice, don't even think about it
I certainly wouldn't include a high quality scanned signature on a public website. But there are a lot of signatures out there, often from very public figures, on corporate documents and reports.
If you scan your signature at a very low resolution, it may be recognisable as your signature but nevertheless be of insufficient quality for people to use in forged documents.
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