Another method would be to allow potassium to burn in the presence of chlorine gas, also a very exothermic reaction:

  
    
      
        
          2
          
          K
          +
          
            Cl
            
              2
            
            
              
            
          
          ⟶
          2
          
          KCl
        
      
    
    {\displaystyle {\ce {2 K + Cl2 -> 2 KCl}}}

References
Further reading
Lide, D. R., ed.
Toxicity
The typical amounts of potassium chloride found in the diet appear to be generally safe. In larger quantities, however, potassium chloride is toxic. The LD50 of orally ingested potassium chloride is approximately 2.5 g/kg, or 190 grams (6.7 oz) for a body mass of 75 kilograms (165 lb). In comparison, the LD50 of sodium chloride (table salt) is 3.75 g/kg. Intravenously, the LD50 of potassium chloride is far smaller, at about 57.2 mg/kg to 66.7 mg/kg; this is found by dividing the lethal concentration of positive potassium ions (about 30 to 35 mg/kg) by the proportion by mass of potassium ions in potassium chloride (about 0.52445 mg K+/mg KCl). Chemical properties
Solubility
KCl is soluble in a variety of polar solvents. Solutions of KCl are common standards, for example for calibration of the electrical conductivity of (ionic) solutions, since KCl solutions are stable, allowing for reproducible measurements. In aqueous solution, it is essentially fully ionized into solvated K+ and Cl− ions.