Black is Black? not on your life... having been a body man full time after HS till I was 26 and then part time since, about 28 years in the field just try and use any black and chance's are it will not match. Some black paints have a grey cast to them and u cant tell till u put one next to the other .. Dupont in the mid 80s came out with what they called a Euro black in addition to their #99 black line. Go to any paint supply house and there will be plenty of options of black and all will be slightly different.. the one that I have good results with on my bike is PPG 9850...
Getting back to the question , the problem with touching up a chip is that the paint has a clear coat and its hard to get the same shade without it .. but a small chip shouldnt be that noticable ..
Clean the area with tar & wax remover , take a match stick (cardboard type) and dip the torn edge into the paint touch up the chip let dry and keep doing this till its slightly higher than the paint . Then take a piece of 1500 grit sand paper and level it out, helps to use a paint stick as a sanding block I prefer the aluminum type. smooth the pain till its dull all around the edge of the chip, this means its level . use some micro finish compound and hand rub the spot be carefull not to over due any of the steps as the clear isnt all that thick.