Poser exports OBJs using its standard scale. What scale you use when importing into C4D is completely up to you, as long as you convert it back to Poser scale when you are done editing. That's how I do between 3DSMAX and Poser. When importing Poser OBJs into MAX, I scale it up by a factor of 250, and when exporting back, I scale it down by a factor of 0.04. But it could be any other scale factors - MAX doesn't care, so it's a personal preference of mine.
If you want to match ZB scale, you could export to ZB using GoZ and then save the OBJ from there. But that would complicate things, since you would have to scale it back down to Poser size, and you wouldn't know what scale ZB used. Actually, Poser already works with OBJ, so we don't have to export anything, unless you are working with morph targets. But even in that case, just pick a scaling factor you like and make sure to scale it back when you're done. ^^