I don't know what you mean by "converting the RGB files to that printer". You select a working colour space for adjusting your photos - if your images are 16 bit, ProPhoto is a good colour working space to use; if your files are 8 bit, Adobe RGB(98) would be more suitable. Set-up your SOFTPROOF in Photoshop to contain the printer profile and the Rendering Intent you will use for printing. For example, if you are using say Epson Enhanced Matte paper, and Relative Colorimetric Rendering Intent, create a SoftProof condition with these selections (View>Softproof>Custom). You can toggle the softproof display on and off with CTRL Y.
Assuming your monitor is properly calibrated and profiled, and above all not too bright, make sure SoftProof is activated with the Printer Profile you will use for printing. Look at the image. If you don't like what you see, use Curves and/or HSB Adjustment Layers to fix luminosity and colour to your taste. Save the image.
When you print, in the Print dialogue, make sure you Let Photoshop Manage Color, make sure you have the same printer profile and Rendering Intent selected in the Print dialogue window, make sure Printer Color Management is OFF in the printer driver, make sure the correct paper is selected in the printer driver, then print. What comes out of the printer should be a reasonably close approximation of what you see on the display.