Try bending it like this and tapping gently with your nail of the other hand and it will shake it loose.
^^^^What Christi said. Cut the pouch and prepare it before starting the test. Flick the bottom of the pouch with your finger a few times to break it loose and put it on the bottom of the pouch. I think I have a video somewhere of how to do it. I never having any problem getting all the powder in the test tube. If you do spill a little don't sweat it. The reagent is in excess in this test.
Because there is more in the pouch than it takes to react with any amount of phosphate the photometer can measure. The photometer reads the result of the reagents reaction with phosphate. If there is more than enough to react with all the phosphate the excess has no effect on the result. If you think about it, otherwise you would have to know how much phosphate is there before the test....to add the right amount of reagent. It's not a titration test. The sample size is much more critical.