It really depends on what the document is and why you need it certified. If it is for a company or a government office, they will probably give you a list of people they will accept, such as magistrates, police officers, doctors, lawyers etc. It is usually enough for the person to write on the copy "I certify that this is a true copy of ..... , sign and date it and add their name and address and qualification. I have done it several times, describing myself as a retired police officer (even though that category is not on the lists). I have one to get done, and I am going to ask a friend who is a magistrate. It does not require a rubber stamp, but the person may be contacted to verify their signature.