First, the recommendation is specific to target crops, so confirm that you're after a lawn (perennial ryegrass) and not veggies or shrubs. Some soil tests will give multiple recommendations depending on the target plant.
Second, you look at the proportion. There's a range for nitrogen, so to make it easier, I'll go with a middle number. You're looking for something with an NPK ratio of 4-3-0.75, or 8-6-1.5, or 16-12-3. Basically, something with the last number smallest, and the middle number about 4 times bigger, and the first number a little bigger than the middle number or about 5 times bigger than the last.
You're probably not going to find anything exactly matching. But that's ok. The easy way is to mix fertilizers that have only one number with the rest at 0...but you shouldn't mix chemicals you're not familiar with...so what you can do is apply at different times.
For this example, I'll use a 10-0-2 (typical of lawn fertilizers, and first number 5 times the last) and super phosphate 0-18-0.
Third, check how much space you have relative to the recommendation and cut down accordingly. This is based on 1000 square feet. For my example, I'll say I have a 270 square feet yard (30ft x 9ft). That means my yard is (270/1000 = 27% = 0.27x) the given area.
We take the npk and multiply by the smaller size. This means the 4-3-0.75 recommendation is 1.08-0.81-0.20. I'll say 1-0.8-0.2 to make the math easier. For my lawn, the recommendation is to add 1 pound of N, 0.8 pounds of P and 0.2 pounds of K.
Starting with the 10-0-2 fertilizer. We'll need 10 pounds. Because 10% of 10 pounds is 1 pound N, and then 2% of 10 pounds is 0.2 pounds. So this gives exactly what we need for N and K.
Then with the 0-18-0. Here's the algebra: I want 0.8 pounds of P, and have a fertilizer that's 18% (0.18) P by weight, with X being how many pounds I need of my fertilizer:
0.18X = 0.8
X = 0.8/0.18
X = 4.444...
So I need 4.44 pounds of the 0-18-0 super phosphate.
That phosphorus number is higher than I would expect for a lawn. I wouldn't reapply that again until another year and another test.
I hope the math makes sense.
PS. The recommendation also recommended application of sulfur (probably to decrease excess pH). It doesn't specify an amount. However, the phosphate application will also decrease pH so if you do apply sulfur, do so sparingly.
