some of these rivets are microscopic in the fenders

do you use a blunt needle or toothpick? paperclip

some of the rivets I couldn't see with out my opti-visor

I am assuming they press easy being thin brass but I don't want to put a hole in it either

You can use a sharp and wet toothpick,or better a wax pencil like this:
http://www.ebay.com/itm/4pcs-xRhinestones-Picker-Pencil-Nail-Art-Gem-Jewel-Pen-Picking-Tool-Wax-Crystal-/391253844709?hash=item5b188be2e5

He means embossing rivets, etc.
I use the back end of the correct size drill bit mounted in my pin vise to do rivets and bolts. A pencil or ball point pen works for embossed lines.