Did you have a soil test that suggested how much you need for the season?  It is a 0-0-50 fertilizer and the amount needed can vary greatly.  You can put this down with a spreader but would need to test the rate at a low setting since spreaders are all different.  If the test calls for 1 lb of potassium per 1000 sq. feet, then you would need only 2 lbs of the potassium sulfate over 1000 sq. feet to reach this goal.  To test it you would have to set the spread setting so the opening is nearly closed and check a premeasured weight of this fertilizer over a marked off 1000 sq. feet and then measure what is left over once it has been applied.  If larger amounts are need than use multiple applications spaced 4 weeks apart.  One point though...many sites in Midland have sandy soil which is often already acidic.  If you add potassium sulfate it will increase the acidity.  Please make sure this application is based on a soil test or it may make it harder to grow grass if it becomes too acidic.

I applied it due to becoming impatient and wanting to try things out. My lawn test advised .83lbs per 1,000 with several applications of 0-0-50. I picked up Lesco 50lb 24-0-11 fertilizer and thoroughly mixed 5lbs of the K2SO4 with it, coating the fertilizer pellets with the powder. I then applied the Lesco fertilizer with the recommended settings for my spreader. It applied very well using this method and figured at that rate I couldn't over do it as long as it spread evenly. I never saw any clouds of powder being dumped so I assume it got applied evenly. My lawn's PH came back neutral and I still have 10lbs of K2SO4 to use up. I won't use that but will look for straight potassium. Do you have any recommendations for a granular potassium product? 

Online source of both granular muriate of potash 0-0-60 and sulfate of potash 0-0-50 are available through retailers.  I could not tell you where it might be locally to Midland.  Many of the stores listed online are common hardware stores and garden centers.