[Alegun]

Код:

function sfg(ds: string): boolean;
var
 i: integer;
begin
 Result:= false;
 for i := 0 to Screen.Fonts.Count-1 do
  if Screen.Fonts[i] = ds then Result:= true;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
 if not sfg('myfont') then AddFontResource('myfont.ttf');
end;