If you are sure you have to rehome him, then contact Samoyed Rescue:
http://www.samoyedrescue.co.uk/
They will have a list of people waiting to give a home to a rescued Sammie and will do home checks and keep in touch with the new owners and offer any advice needed.
Do not give him to the RSPCA.
Please be totally honest with the rescue people about his nature, his temperament and any problems - this will give them the best possible chance of finding him the right home. They will not judge - their only interest is in helping the dog find a permanent loving home.
Genuine show people would take very good care of him, although I doubt if genuine show people would be interested in a dog of this age. Most would want a puppy
and would have booked one well in advance from a breeder of their choice. As he appears not to have been shown or exhibited, his value as a stud would be non existent other than to unscrupulous people who think they are getting something for nothing.
I hope you will think long and hard before taking on another dog. Although I don't know your circumstances, having rehomed two dogs in such a short time, you need to consider whether you are ideally situated to keep a dog.
I do hope you do the right thing by him.