ethereum - How to generate sign to pass to transferPreSigned(), contract is not asking for sign while transfer()

Question

I'm creating ERC865 token so that users can send tokens without having ether. I followed 1 and 2.

As per 1, sender will sign transaction object while calling transfer() but I'm unable to see any "Sign"! What parameters should be passed to transferPreSigned()? I'm using Metamask and Solidity.