People have as many reasons for wanting to surrender their Doberman - some sad, some faced with no other choice, some in the dog's best interest and some boneheaded. The rescue group will not judge - their only interest is the dogs safety.
You should first contact the people where you aquired your Doberman, be that a breeder, a shelter or indeed another rescue group - there is often a requirement to return the dog if you cannot keep them. If you contact a rescue groups remember they are volunteer organizations - and many do not have a kennel facility where you can simply drive up and drop off your Doberman. If you are moving out of the country, if you are having a divorce, if you are pregnant - what ever the reason you don't think you can keep your Doberman - then think ahead - call rescue and give them a heads-up. They will need time to find the right foster home for your dog.
Another reason to contact rescue early is that they may be able to offer advice or assistance that will enable you to keep your Dobereman. The behavior problem that you may see as intollerable may have a solution that the Rescue group can help you with.
If there is no other option but to relinquish your dog then be honest with the Rescue group. If your dog eats couches or cats - tell them.
There isn't much they haven't heard, but they need to know so that they can best place your dog, where they will not be a
danger to others or to themselves. Whatever you do - don't list on Craig's List as "Free to Good Home" - people do not value something that they
got for nothing, and worse they may just be 'flippers' who will sell your dog on to the
next highest bidder.
Even if the Rescue group cannot take your dog they may be able to list it on their website and also help you pre-screen would be adopters.