Duraliegh is certainly right about the feathering, because of the vertical wall, the mix needs to be stiffer to have it stay in place - a wetter mix feathers better. However, sponging the edges will lessen the 'bump' or ridge and will help blend new to old, colorwise. I assumed from your original post that this was just phase 1, stuff you could do yourself, and was temporary, until you could find a contractor to replaster the body of the pool. As such, some imperfection still allows use of the pool and it's not an asthetic nightmare, if my assumption was incorrect, I appologise
(I see that Duraliegh has responded while I was being distracted by houseguests [2 of them both 4 legged, 1 a 6 mo old puppy] mayhaps a synthesis of the 2 answers will provide the solution).
Again, if you've anymore questions or are in need of clarification, ask away!