The marks are from the stepover value set in the parameters.you change that and the marks shoud dissapear. there is another parameter that might help called wall scallop height. if set will make the marks smaller or dissapear. I try not to use the scallop height parameters because it adds a lot of time to programs. I just calculate the stepover value to clean up the cutter marks. (Example)A 1/16 diameter end mill with a step over of .003 should leave a cusp height of .00004 when using the surfacing routines.