There is a distinct difference between reassuring your dog and supporting them. Contact should be offered to not given.
Allow your dog to take contact from you where and when they choose. The further back along the body they choose to make contact, the lesser support they need. If they need support in the shoulder area, they are feeling very insecure.
If they make contact in the middle of their body, they are feeling a little more confident. If they ask for support on their hindquarters, they are more relaxed but still need to feel contact.
After this stage, you will notice they will move away from time to time and only return to you for a 'boost' of support. Over time, they will become confident enough to move away and just glance back at you, knowing you are there if they need support.