VBA Filldown or Autofill

Hello!

I've Frankensteined the excelgeocodingtool.com spreadsheet for work and added another sheet to give me the trip duration and kilometres. My issue is that I have to manually fill down the relevant formula everytime which isn't super user friendly for my colleagues.

I've tried

Range("A3:A" & LastRow).Formula = "=SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(distance.url,"$1",$F3),"$2",$S3),"$3",travel.mode),"$k",bingMapsKey)"

but I'm getting an error saying that the $ sign is invalid.

Is there a way that I can get the formula to fill down using VBA without including the formula in the code, or is there something else I should try?

Thank you