Why are you confused? What do you want to achieve? What do you need those liposomes for? We can't help you if you don't give us more details.
Why don't you simply try different amounts/ratios? What about starting 1% w/w and then go up or down? You will have to purify the liposomes anyway, so a moderate excess of CFSE won't be a major problem.
Thank you Marco for your help. Finally I want to encapsulate the CFSE inside the liposome. I was thinking that if i take too much CFSE like 1mg/ml will affect the liposome formation. Now i am clear. I am thinking to weight out 10uM cocentration CFSE in 1ml. What would you like to suggest me? Many thanks