Welcome to Just Answer. I will do my best to fully answer your question(s).
If your faucet is in fact leaking around the base of the faucet O-ring number(NNN) NNN-NNNN1000949, and(NNN) NNN-NNNNwill need to be replaced. But if you also have water under your sink I suspect the handheld spray portion may be leaking as well and in need of replacement entirely. To access the formentioned O-ring you need to pry off the white handle cap with a small pointy object (end of Knife or a sort of pic) then remove the screw and take off the handle. Next (after shutting off the water to the faucet you mustdisconnect the sprayer hose under the sink and remove the weight attached. then pull the sprayer unit all the way out of the faucet. Under the handle you remove part number 78064 by unthreading it and then the faucet base should pull up to access all the parts in need of replacement. Now I recommend calling kohler directly to order your parts and speak with them about any other parts they recommend you get as well. They ship directly to you at no charge for parts.