@woreign:
There isn't much detail in the description, but from the parts list it looks like it has everything you need to put two sets of reef points into the sail, plus some hardware to rig one reef line for the rear and one for the front.
Sailrite is a pretty reputable place, so I'd expect that if you follow their instructions you end up with a workable reef. I've not tried to modify any of my sails, so I don't have any input on that part of the process, but it's not difficult to find it
discussed online.
I do have experience setting up the reefline and associated hardware (and using other people's setups on other boats). From that experience I can tell you that if I did things over, I would use a reef hook at the gooseneck instead of a forward reef line (theirs is cleated to the mast which some DS owners report doesn't work well for the DS). With a hook (for example from D&R Marine), you simply pull down the sail until the new tack grommet goes over the hook and tighten the halyard again. And you don't need to double the setup if you want to be able to use both first and second reef in your sail.
For the rear, they provide the pad eye to which you knot the reefline. Then it goes up and through the new clew grommet (for the first reef) and then to a cheek block (not bullet block as they write - they do show a cheek block). The block is attached to the side of the boom, a bit back, so the reefline pulls not only down, but also backwards (like an outhaul). From there it goes forward to the cleat on the side of the boom. Forward, so you can operate everything from one position standing in the forward end of the cockpit.
I'm sure the line they include for the reefline works pretty well. I'm using some more modern rope that allows really tiny diameters while still being strong. I prefer that for lines like this which only need to be used occasionally. But that's a matter of taste.
If you were to get the kit but used of reef hook in the front, you could get a second cheek block to use for a second reef line; for some sailing areas (like sailing the Texas 200 you definitely need multiple reef points, in other places it's almost overkill). You would need to purchase a bit more rope, I'm sure the length they include is intended just for the first reef, but then you could have both reeflines permanently installed.
The stuff included in the kit for placing the grommets and reinforcements looks right - they chose grommets that you can screw together which is probably a good choice if you don't have a good way to set grommets with a press. Not being able to read their instructions, I don't have an opinion on how easy that part (modifying the sail) will be.
There are some parts that I don't recognize. There's some shock cord, some plastic clips and what looks like a roll of white velcro. There's nothing in my setup that looks remotely like that, so I can't give you any hints. If you do a bit more searching on the internet you might find out more.
(If you type "site:forum.daysailer.org sailrite" into any search engine you will get all mentions of sailrite on this site).