In the Gelugpa Tradition of Tibetan Buddhism of the FPMT one is expected to take refuge in the three jewels (Buddha, Dharma, Sangha) twice daily (three times each), especially if one has already taken refuge formally.
For me, as a former theosophist, anything sectarian is a problem. On the other hand, I did pick Buddhism as my spiritual path of preference for a reason and I do trust my teachers when it comes to the path to enlightenment and buddha-hood. So I took formal refuge and became a Buddhist.
In order to not lose touch with the foundation of my path: universal wisdom and remind myself of my new commitment, I composed the following refuge prayer for my daily practice:
“Till my enlightenment I take refuge in Buddha, all Enlightened beings and my own Buddha Nature;
I take refuge in the Dharma, the universal truth and the path towards enlightenment;
I take refuge in the Sangha, the community of those who are ahead of me on the path.”
Refuge is a universally Buddhist ritual, practiced by Theravada, Zen and Tibetan Buddhists alike. In itself it does not yet determine which type of Buddhism one has chosen.
In the FPMT taking refuge, like other vows, is sometimes also taken as choosing a particular guru as one’s teacher. This part is definitely not mandatory: no teacher would expect you to wait with taking refuge till you are ready to choose a particular teacher as ‘your teacher’.