can i create an electronic signature to sign a PDF and return in a PDF format?

Sure. You can insert an image (or perhaps other option) onto a pdf using Preview or Acrobat Reader. Acrobat Reader has a built in tool where you can type your name, draw your signature, or use a file (image) you have previously made to sign. Most folks using forms of some kind may also have a signature request built in. Then just save the file and send it back