If you are talking about the Digitech rp300 guitar modeling pedal, then yea you sure can, and should. I use a 414MKII and a BP200 ( bass version ). Just plug your guitar into the rp300 and the output of that into the dedicated guitar input on the lower rear panel of the 414 and set the track input to " guitar " and slider between 7 & 8 , trim all the way down , and use the guitar input trim knob ( next to the input on the back ) to adjust level.
You might need to tweek the output level of the rp300 also. I use my bass pedal for bass and guitar because I like it better than the guitar models, as it has 16 amps and 6 speaker cabinents including a bassman and a dual showman. The reverb and delays and compression, ect are the same as the guitar models.
Good luck !