If I use ketchup for fries (which I do about half the time), I like to fill up one of those little paper thimble thingies they have for condiments and dip them. Or, pool on the side. Never on the fries themselves. I often also like to dump a couple of those little packets of pepper into the thimbles of ketchup.
But I prefer vinegar on my fries if I can get it. Or Tabasco-style vinegary hot sauce. That’s probably my favorite condiment. Vinegar gets splattered on the fries. Hot sauce gets dipped.
Salt and vinegar on fries. Most places with decent fries offer vinegar, and some of them do not offer ketchup.
I will put ketchup on weak fries, and a lot of pepper. Sometimes I cover them. Sometimes dip. Places sell fries but not burgers, so that’s not always a consideration.
Pool on the side.
My GF, however, will pick up one fry at a time, apply a fine bead of ketchup directly along its length, and then eat it. She is amazingly precise at applying that bead, even from a hand-torn McDonald’s packet.
No ketchup.
Because that would be a different poll. 
The premise of the question assumes you like Ketchup on your fries.
For the record, putting the ketchup in a little cup or on a napkin etc. would be pooling. It is funny that on top is doing so poorly because whenever I am in a place that fries are served it looks like many people just smother them in ketchup.
My objection to this is that smothered fries soon lose their nice texture and become soggy - you’d have to snarf them down quickly to avoid this.
I like to make them last, so it’s “pool & dip” for me.
That would be like eating air.
Side pool. Add a few drops of Tobasco sauce and mix it up with the first fry.
I’m not totally clear on the ‘ketchup and fries’ thing 
On a non-related topic I dash a small helping of tomato sauce over the pile of chips on my plate.
I’ve been covering them so far, but only because I hadn’t considered the pool-to-the-side technique. I think I’ll try that next time.
I don’t put ketchup on fries. We folks who grew up in South Eastern Idaho know that brown gravy is the proper condiment for fries. But with the gravy I’m, a dunker not a coverer.
I like to cover them if it’s ketchup. Personally I prefer them with some mayo though.
[Casino Royale]*Oh, I don’t know, really. I suppose we’ll be doing a bit of both, then! * [/CR]
Only if you only eat really crappy fries. Good fries have flavor. Ketchup is for the fries that don’t.
We eat fast-food at home; I go to the drive-thru and pick up fries, and the rest of the meal, at the window. At home, we use a ketchup bottle, not those little packets, which are hard enough to tear open anyway. I always pour ketchup on. The only disadvantage is that the ketchup is cold and the cold is imparted to the fries.
Tabasco!
If I get fries (with or without a meal) at the drive-through, there are usually none left by the time I get home.
I like a ton of ketchup, in a pool to the side. I add more as the pool depletes. And it’s gotta be Heinz; Hunts is for c*nts.
In a separate container, mixed with hot sauce and a bit of whatever BBQ sauce is around, if any.
This is why planning is important. If I’m coming home with fast food, the wife will put the ketchup out 30 minutes or so before I get home, because she knows I hate cold ketchup on my fries. The price you pay for having First World problems, I guess. 