Do  bit of math before you render, and figure out where you want to print the image (CMYK publication - 300dpi, injket or photo lab where you can get away with 150dpi for the size, etc.) and enter those pixels.

Example  - you're gonna have it published, and it's gonna be an 8x10 that they'll need at 300 dpi. What you enter into Bryce for render size is 2,400x3,000 pixels. It will render them at 72 dpi but that doesn't matter - dpi is a "parameter" while the actual "pixels" are the image. Simply change the parameter to 300 dpi afterwards in Photoshop or PhotPaint.

In Photoshop, "Resample" actually means something which is why you turn it off or it'll mess with your pixels.

Hope this helps-
-Lew ;-)