Most of the TLRs do not come with built-in meter.
For TLRs come with built-in meter, most of these may not fully functional due the its age, or some functional but may not be accurate.
In these cases, a good exposure is very useful.
Managed to got a e-copy of Zeiss Ikon Ikophot exposure meter instructional manual, free download here.
TLRgraphy 
Thanks for posting the instruction booklet for the IKOPHOT meter. I have just this day bought one from a junk shop off Byers Glasgow, it will go well with my IKOFLEX. What a good afternoons rummage, same shop also found a Weston MKV wilth defuser all leather cased and boxed thirty pounds for both. Bargin, who can tell however I am please.
That sounds awesome! I am using my ikophot with my ikoflex 🙂