The serial number will be in a convenient location: the butt or frame of a revolver, the frame or slide on a semi-automatic pistol, the action side of a rifle, the bottom or action side of a pump-action or semi-auto shotgun, or the action flat of a break-action shotgun.
If you have a Rigby rifle it has a serial number some where, you just need to find it. Rigby has records of all their rifles and who it was initially sold to.
However, You did not say it was a Rigby just that you purchased a 275 Rigby.
If you provide the maker of your 7 X 57 firearm, members would have a better opportunity to assist you.
