NewPing Library: HC-SR04, SRF05, SRF06, DYP-ME007, Parallax PING))) - v1.7

Sorry, I forgot to include my environment info:
MAC OS X 10.6.8 Snow Leopard
Arduino 1.5.4
Hardware is an RFduino, version 1.7, with the HC-SR04 sensor.

When I try to compile a sketch that includes the NewPing library, I receive the following error:

In file included from echo_sensor_test_NewPing_lib.ino:1:
/Applications/Arduino.app/Contents/Resources/Java/libraries/NewPing/NewPing.h:113: fatal error: avr/io.h: No such file or directory
compilation terminated.

I can't find any information about the avr/io.h file or the avr library to tell me where to find it or how to load it .

I am new to this, and didn't find any information about this error.

john