I use that config for my RX580 and my hashrate on pool is the same as the miner :

   { "mode" : "GPU", "worksize" : 8, "alpha" : 64, "beta" : 8, "gamma" : 4, "delta" : 4, "epsilon" : 4, "zeta" : 4, "index" : 1, "multi_hash":944 },
   { "mode" : "GPU", "worksize" : 8, "alpha" : 64, "beta" : 8, "gamma" : 4, "delta" : 4, "epsilon" : 4, "zeta" : 4, "index" : 1, "multi_hash":944 },

i tried beta 16 but got lower hashrate