So I picked up a set of Kensights for my old man that we plan on putting on his Kimber Classic Stainless Target.

We just had the pistol completely cerakoted, and decided that since the old sights were off, we'd upgrade them.

Rear sight I had no issues with. Not a single one. It was snug, but I didn't have to force it in. Nor was it a sloppy fit. A brass punch and a few taps was all it took.

The front sight doesn't even want to start. Like, not even a sliver of the way into the dovetail.

What's the proper technique to fitting it? I'm not even sure where to start. The only sights I have installed prior is on my 3 Glocks.

I'll give this a shot for starters and see if I have any luck.

If you decide to file the dovetail go slow, little at a time. I got impatient with a Smith M&P and had to buy a new front sight.

When one files on something to fit a dovetail where do you file?   Thanks material of the bottom of the sight?

Troll around to some youtube videos, they have tips on how or where to file, I usually put gray sharpie on it and try to
fit it and see where it rubs off the marker, that's where I file.

Just 'cause it's on YouTube doesn't mean it's the correct way.  

But your method makes sense.

Check out Dawson precision website. They have videos on how to do front sights.
   I file the cheapest part like was said already. Leave the paint in the dove tail, you might take too much paint off and have shiny metal showing on the sides of the sight once installed.
  I always make it a very tight fit and also locktite everything. Put some locktite in the dovetail and on sight then clean up the extra that comes out after instal. Even the rear sight gets locktite in the dovetail and the set screw.  That's the way Dawson does it. I assume they know what they are doing.

Set screws should also be flat and not pointed or cupped.

While both points and cups provide more strength against slip they also limit the ability to adjust.
They deform the metal they are tightened against and if you need to move the part a small amount they will pull it back to the old location when tightened.
You would have to fill the old deformation with a welder, file it back to smooth, and then you could move the sight 0.010".

Good luck with that.