Linda...are you making your own fondant? I make MMF and color it red at the melted marshmallow stage, much easier to incorporate that way...I use a combo of wilton colors....pink, red-red, no taste red, christmas red and burgundy and that gives me a deep rich red color perfect color for fondant roses.
I make my own fondant, which tastes better than some that you can buy. Also, it is much cheaper. Adding the colour to the melted marshmallow stage sounds pretty easy.
I forgot to add that the color will deepen as the fondant "ages" (ie: sitting out overnight). but light pastels (pink purple etc) will fade if overexposed to light.
My recipe for RED fondant... Satin Ice Red.... sorry but I just love the color it comes in and might be a bit more expensive but I don't have time to play with it and mix my own so I just buy it.