Roberto Boker y Cía

Apartado (P.O. Box) 148, Coliseo Viejo Num. 1., Mexico City

This firm produced perfins from 1899 to 1903.

Here is a Roberto Boker & Cía cover produced in that time:

Used 24 December 1903 from Mexico City to Tampico, Mexico
"R.B./&C." perfin on 5 centavos Coat of Arms definitive (1903) - Scott 307

Here are some of the stamps which have "R.B./&C." perfins:

Roberto Boker y Cía stores, then and now.