Search for a letter in a string column in a dataset

I want to check if a string column in a dataset (for example, Name) has the letters "a" or "A". If so, I want to create a dummy with value 1. I have tried something like this:
Data1[All,
Append[#,
"Dummy1" ->
If[StringMatchQ[ToString[#NotaryFirstName], "A"]= True, 1, 0]]&]

but I get an error that says: StringMatchQ Tag in StringMatchQ[Annesha, A] is protected.

Please help