Adjusting the riving knife on your table saw is easily carried out.
As always the very first thing you should do before you do any maintenance or repair work on a table saw.

Firstly unplug the machine from its power source. Raise the blade then remove the blade insert or throat plate.

A good way to check the alignment is to sight down the length of the blade and you should be able to see if the riving knife is sticking out to one side or the other.

You can check to see whether the riving knife needs adjustment by eye. An alternative is to use a ruler. Using a ruler as a straight edge rather than a spirit level is because the ruler will go between the blade's teeth. The riving knife is the same thickness as the steel of the blade not the carbide tips and because the ruler needs to go against the steel of the blade and avoid the carbide, the ruler is the best option. If the ruler is on the carbide tips you won't get an accurate reading to the riving knife.

For the actual adjustment of the riving knife an allen key is the right tool. The riving knife has two directions of alignment, vertical and horizontal. Horizontal alignment is adjusted with two bolts
Vertical alignment is adjusted through a set screw located right next to them.

Because you don't know if your riving knife is correctly aligned vertically you need to check your horizontal alignment at the very base. To adjust the horizontal alignment loosen off the two bolts but not too much. It needs to be just tight enough that it will still hold steady when you move it and not wobble from side to side.
With it loosened off like this all you need to do is lay your ruler across the blade remembering to keep it on the steel and align the riving knife right up against the side of the ruler then tighten the bolts
After you tighten it up check it again because it does tend to move a little bit as you tighten the bolts. Also remember to check both sides of the blade

Once the horizontal adjustment is done you need to check your vertical alignment. The way you check the vertical alignment is by checking at the bottom and the top of the blade.

Mine is pretty well aligned at the bottom but the top has quite a gap
Tightening the set screw moves the riving knife to the right. Loosening it moves it to the left.

Once the adjustments have been done replace the throat plate back on. Check the riving knife alignment every couple of months maybe even more often. All it takes is a bad knock to the riving knife and it will push it out of alignment.