Laravel 5.5 use custom validation rule in validation request file?

Is it possible to use my custom validation rule in a validation request file?

i want to use my custom rule called EmployeeMail here is the code of the request file

class CoachRequest extends FormRequest
{
    /**
     * Determine if the user is authorized to make this request.
     *
     * @return bool
     */
    public function authorize()
    {
        return true;
    }

/**
 * Get the validation rules that apply to the request.
 *
 * @return array
 */
public function rules()
{
    $rules = [];

    if ($this->isMethod('post') ) {
        $rules = [
            'name' => 'required|string',
            'email' => 'required|email|employeemail', <<<--- this
            'till' => 'required|date_format:H:i|after:from',
        ];
    }

    //TODO fix this
    //TODO add custom messages for every field

    return $rules;
}
}

it gives me an error when i try to use it like this

Method [validateEmployeemail] does not exist.

code of custom rule

namespace App\Rules;

use Illuminate\Contracts\Validation\Rule;

class EmployeeMail implements Rule
{
/**
 * Create a new rule instance.
 *
 * @return void
 */
public function __construct()
{
    //
}

/**
 * Determine if the validation rule passes.
 *
 * @param  string  $attribute
 * @param  mixed  $value
 * @return bool
 */
public function passes($attribute, $value)
{
    // If mail is that of an employee and not a student pass it
    return preg_match("/@test.nl$/", $value) === 1;
}

/**
 * Get the validation error message.
 *
 * @return string
 */
public function message()
{
    return 'Email is geen werknemers mail';
}
}

can i only use this custom rule like this?

$items = $request->validate([
    'name' => [new FiveCharacters],
]);