A common method is to send it back by fax. Just get the fax number of the other company and fax the stamped PDF file to the other party. Another method is to print and stamp and scan it back. Print the received PDF file, stamp it, then scan the stamped file into PDF format and send it back to the other party by email. This method is cumbersome, and black and white color files may be printed when printing. Moreover, there is a more convenient way to use electronic signature technology. You can use special electronic signature software to electronically sign a PDF document, and then send the signed document back to the other party by e-mail. This method is not only quick and convenient, but also has legal effect.