Edit the signature line and replace it with an image instead
Admin CP >> Templates & Style >> Templates >> YOUR THEME >> Post Bit Tamplates >> postbit_signature
Replace the code with this
Admin CP >> Templates & Style >> Templates >> YOUR THEME >> Post Bit Tamplates >> postbit_signature
Replace the code with this
<center><img src="https://i.servimg.com/u/f44/17/34/84/29/217.png"></center>
{$post['signature']}