Extending AuthPage
Anyone have any suggestions on how to extend the AuthPage's RegisterPage to include additional input fields?

RegisterPage as you desire. And use it in the Refine component LoginPage as 
useFormProps is compatible with useForm from the @pankod/refine-core package so you have to pass the useFormProps to refineCoreProps for @pankod/refine-react-hook-form package like below:export const AuthPage: React.FC<AuthProps> = (props) => {
const { type } = props;
const renderView = () => {
switch (type) {
case "register":
return <RegisterPage {...props} />;
case "forgotPassword":
return <ForgotPasswordPage {...props} />;
case "updatePassword":
return <UpdatePasswordPage {...props} />;
default:
return <LoginPage {...props} />;
}
};
return <>{renderView()}</>;
};RegisterPageLoginPageconst App = () => {
return (
<Refine
authProvider={authProvider}
LoginPage={AuthPage} # <<<======== Your custom AuthPage goes here
resources={[{ name: "posts" }]}
/>
);
};useFormPropsuseFormProps@pankod/refine-core@pankod/refine-react-hook-formimport { useForm } from "@pankod/refine-react-hook-form";const {
register,
handleSubmit,
formState: { errors },
} = useForm<BaseRecord, HttpError, RegisterFormTypes>({
refineCoreProps: {
...useFormProps,
}
});import { UseFormProps } from "@pankod/refine-react-hook-form";