Sorry... no first name listed... here's what i found...
1862-63 MARSHALL, R.M., Confectionery, Candy Manufacturer, and Cake Baker, 75 Main, h 41 Madison(first one is business, second one is home address)
1864-65 MARSHALL, R.M., confec, 75 Main, h 358 3rd
1866-67 MARSHALL, R.M., confec, 75 Main, h 38 Ludlow
not in 1868-69 or 1871-72
1868-69 does list Patton & Scheffel, confectioners, at 75 and 77 Main(they aren't listed in the 1862, 1864, or 1866 directories, so it doesn't appear that R.M. actually worked for them?looks like he operated business under his name, then somebody else took it over maybe?)
anyways... not really what you were looking for... but hope this is of some interest....