>Should she go back to the breeder or should we try and sell her?
Her breeder should certainly be contacted in the first instance. Hopefully she's one of the reputable ones who takes a lifetime interest in their litters, not just 'take the money and run'. It's possible she will have a waiting list of people wanting a puppy. It can be very hard to sell an older puppy - most buyers want a baby puppy, and once they're over about 14 weeks they become less and less 'desirable' unless they're well-bred and from a well-respected breeder. A breeder like this will have the contacts that you naturally don't have. A 'private' owner selling an older puppy will be lucky to get about £150-£200.
>If she goes back to the breeder should we get any money back from her?
You might get some money back for her; not necessarily up front but after she's been homed, less expenses.
>Do we sell her or rehome her for free?
People who get free puppies are sometimes (not always) the sort of people who'll sell them on again for a profit or pass them from pillar to post. Not what you want for your girl.
If the breeder is one of the ones who can't or won't help, then contact one of the breed welfare societies for help and advice.
Midlands and Northern Rhodesian Ridgeback Club RescueMrs S M Firth, Oldham, Lancs. Tel: 01457 872520
Rhodesian Ridgeback Welfare Trust Mr B Davies, London. Tel: 020 7485 0691
Southern Rhodesian Ridgeback Association Mrs Marie Rose Crunden, Hythe, Kent. Tel: 01303 268305