When I studied Reiki with John Harvey Gray, who studied from first degree to mastership with Hawayo Takata, I recall it being stressed in Reiki 1 that is was very important to ask permission before touching someone to be a channel for Reiki. I stress the importance of this ethical issue with my own students. As I was studying Reiki 2 with John I asked him if we have to ask permission to send Reiki to someone where we are not actually touching them. He was very clear that we did not have to ask permission to send distance Reiki. This I would think is a personal choice to ask permission to send or not. What if you wanted to send Reiki to the troops in the Middle East do you think you would have to get in touch with them before you send Reiki for their highest and best or to say a prayer for them?? No that would be silly. I attended a Reiki conference recently and the speaker tried to express her opinion on sending distance Reiki as an ethical issue which it is not, it, is a personal choice. She did not train with John Harvey Gray. She felt that we should ask permission before sending Reiki. We do not have to ask permission to send Reiki or a prayer. If Hawayo Takata felt that it was important or ethical to the practice of Reiki I am sure she would have impressed upon John that it was necessary. He honored Hawayo Takata, her teachings and upheld them in his 36 years practicing and teaching Traditional Reiki classes.
So send Reiki to your hearts content since it will benefit you and someone else.