Stripe integration in Laravel Application

I am trying to integrate Stripe in my Laravel Application. I am trying to use this (Pay with Card) Service of Stripe.

I am using below code after redirection from Stripe

try {
            $charge = Charge::create([
                'amount'          => $price * 100,
                'currency'        => 'gbp',
                'source'          => $request->stripeToken,
                'application_fee' => 123,          // Here is the issue , if I remove this line it works fine.
            ], [
                'stripe_account' => $stripe_id,
            ]);
        } catch (Exception $e) {
            return back()->withError('Something went wrong while processing your payment.');
        }

I am getting below error