For OSX Mavericks+, Bill Behrman suggests:

https://stat.ethz.ch/pipermail/r-sig-mac/2015-March/011317.html

the comprehensive frameworks provided by William Kyngesburye:

http://www.kyngchaos.com/

Simply install the GEOS framework and all of its dependencies,
then install the rgdal source package from the command line:

R CMD INSTALL --configure-args="" rgeos_*.tar.gz

with the correct configure-args for your platform. Bill used:

install.packages("rgeos", type = "source", configure.args =
"--with-geos-config=/Library/Frameworks/GEOS.framework/Versions/Current/unix/bin/geos-config")

