How to choose SPI type used by RF24 library from application?
Using this RF24 library set, I am able to use or not softspi by doing #define SOFTSPI on my sketch, there's no need to define it on the RF24_config.h, you should be able to define it on your own sketch.

EDIT: 

Arduino 1.6.5

#include &lt;SPI.h&gt;
#include "RF24.h"
#include "printf.h"
#define SOFTSPI //Define pins RF24_config.h

/****************** User Config ***************************/
/***      Set this radio as radio number 0 or 1         ***/
bool radioNumber = 0;

/* Hardware configuration: Set up nRF24L01 radio on SPI bus plus pins 7 &amp; 8     */
RF24 radio(8,9);

....
....
void setup() { ... }
void loop() { ... }