Does 100% rye sourdough bread always have a sticky crumb? How do I make it stick to the knife less?
One cause of gumminess in 100% rye breads is excessive starch degradation related to amylase enzyme actions.  Amylase action is slowed down by increasing acidity.  You can increase the acidity by adding a small amount of lemon juice or cream of tartar to your dough as described here.

In his books "Whole Grain Breads" and "Crust and Crumb", Peter Reinhart comments that you can use ascorbic acid (1/8 tsp / 125 mg per loaf) to increase acidity and inhibit both amylase and protease activity. 

Since rye bread doesn't have significant gluten for structure, but instead relies completely on starches and pentosans, it is imperative to let the loaf cool completely before cutting it so that the starches crystallize and the gums solidify.