I was looking for a little extra push after plateauing on tirz, so I started adding 1 mg of reta around a month and a half ago. I take tirz on Wednesdays, and reta on Saturdays or Sundays. I didn't notice a huge difference right away and was nervous about upping my tirz at the same time, so I stayed put, but after the second week I noticed a difference. I've read it takes a little time to build up in your system, so patience is key! It definitely helped keep my appetite in check while staying on a lower dose of tirz. A few weeks later, I increased my tirz by half a mg and boosted my reta by .5 two weeks after that, so now I'm at 1.5 mg of reta weekly on top of my tirz, and it's really making a difference!
My goal is to continue both until I've dropped another 30-40 pounds, and then I'd like to wean off tirz and stick with a small amount of reta.
I definitely suggest adding it to your routine, keeping the dose as low as possible, and being patient in the beginning. I hope you have the same success!