Health and safety reasons tell you that any oxide of potassium is not going to be pleasant to work with and will react with water (and deliquescence) and carbon dioxide in the atmosphere. Big danger of caustic burns from the heat evolved too.
This is one reason, IMHO, why expressing glass compositions as oxides or oxide content (e.g. Na2O, CaO, K2O) is not realistic or sensible. A better material, from an H & S perspective, to use would be the carbonate K2CO3 or the bicarbonate KHCO3. Both are cheaper and readily available