Installing Ristretto can't find libexif

[Sieranski, Greg]

I am trying to build the current release of ristretto but am having some 
difficulties. When I run .configure --prefix=/home/xxx/....  I get the 
following message:

checking for libexif >= 0.6.0... not found
*** The required package libexif was not found on your system.
*** Please install libexif (atleast version 0.6.0) or adjust
*** the PKG_CONFIG_PATH environment variable if you
*** installed the package in a nonstandard prefix so that
*** pkg-config is able to find it.

libexif is located under  /usr/lib64/libexif.so.12.2.0.
So I added: export PKG_CONFIG_PATH="/usr/lib64/pkgconfig:$PKG_CONFIG_PATH"

but I am still getting the message saying it can not find libexif.

Any Ideas on what I am doing wrong?

Thank,
Greg Sieranski