Sounds like you are well covered then, keep in mind that if you actually NEED potassium that means the methylation supplements are doing their job. Why feel the need to make the methyl folate more effective? Is it not doing the job as of now? what are your symptoms on the protocol as of now? Do you have an increasingly large need for potassium or does hypokalemia symptoms not seem to occur?
Methyl trappers via. Fred's protocol are Folic acid (supplemental and food added) so breads, cereals, protein bars, certain muti vitamins, etc.. Folinic Acid as a supplement, and if you eat a LOT of veggies then you may have an increased need for methyl folate as it can block absorption a bit, Glutathione supplements, Whey Protein powder, and NAC. These all act as methyl trap and bring out paradoxical folate deficiency.