Potassium chloride is used to kill people.
It is used for lethal injections ... AND ... it is NOT DETECTIBLE, postmortem:
Potassium chloride intravenous injection is used in ... lethal procedures for state-sanctioned punishment.
Owing to its relatively high concentrations in hemolyzed blood (25-80 mM) compared to serum (about 4 mM), it is difficult to conclude potassium poisoning by postmortem analysis of biologic samples.
https://pubmed.ncbi.nlm.nih.gov/21923800/
It is also used in the Pfizer Covid (so-called) vaccine:
Here's the complete list of ingredients, according to Pfizer-BioNTech: ... Potassium chloride
Did Pfizer disclose the amount of KCl used in the (so-called) vaccines? No.
Did Pfizer disclose whether or not different amounts of KCl was used in different vials for different individuals? No.
recommended daily allowance for potassium chloride is 4,700mg. Most people are deficient.
I think it would be difficult to dissolve that 4.7 grams into a (typically) 2cc syringe of liquid. A bit like mixing a cubic foot of concrete in a teacup.