Sorry about that, right now, we do not support transferring ringtones to your iPhone. This function is mainly applied to the Android devices. You can customize your ringtone on your Android with great ease. But in the next version of Apowersoft Phone Manager, we will support it. Once released, we will get back to you ASAP.
And at present, you can use iTunes to make your ringtone and then set it for yourself. For more detailed info, please refer to the post as below: