Hello student,
After clearing all of the levels of selection procedure in staff selection committee you have to verify your all documents and you also have to bring all the copies and the original copies of your documents to verify yourself. Basically as per my knowledge the certificates are just authorised copies. So signature on that may not be a matter so much.  But yes signature from your government ID like Aadhar voter PAN card can be considered. So in that case as this is a sensitive case try not to make a huge difference in your signature. Obviously help you about document verification process in SSC
https://competition.careers360.com/exams/ssc-cgl/amp