Ok... after some pondering, think I get what you mean. You're referring to chinese stamp in electronic format.
Here is how you do it:
1. Edit your "e-chinese stamp" to make the background transparent & save it.
2. Open any pic.
3. Start recording action.
4. Click "File->Place..." and open the edited "e-chinese stamp" file.
5. Adjust the placement.
6. Stop recording action.
7. Use the action on any pics you want to add the signature.