Atmega328PB + RFM69HCW library

HI,
I've got a custom board with Atmega328PB (the model with two SPI ports) and RFM69HCW.
Is there a way to use SPI1 to communicate with the radio? When I monitor CLK1 using the following code, there is no signal.

I've been looking through the recommended library but can't see where SPI is defined. Not sure if this is relevant, but I'm connecting to my board via ISP (SPI0), not USB.

My code for the TX Based on RFM69 library sample code by Felix Rusu:

#include <RFM69.h>
//#include <SPI.h>
#include <SPI1.h>
#include <avr/io.h>
#include <util/delay.h>
#include <pins_arduino.h>
// Addresses for this node. CHANGE THESE FOR EACH NODE!

#define NETWORKID     0   // Must be the same for all nodes
#define MYNODEID      2   // My node ID
#define TONODEID      1   // Destination node ID
//#define FREQUENCY   RF69_433MHZ
#define FREQUENCY     RF69_915MHZ
#define ENCRYPT       true // Set to "true" to use encryption
#define ENCRYPTKEY    "TOPSECRETPASSWRD" // Use the same 16-byte key on all node
#define USEACK        true // Request ACKs or not

RFM69 radio;
int val, button;
void setup()
{
  DDRB = 0b11111111;  // all outputs
  DDRC = 0b11111111;  // all outputs
  DDRD = 0b11110111;  // D3 input
  DDRE = 0b11111111;  // E3 output

  radio.initialize(FREQUENCY, MYNODEID, NETWORKID);
  radio.setHighPower(); // Always use this for RFM69HCW

  if (ENCRYPT)
    radio.encrypt(ENCRYPTKEY);
//  PORTB = 0b11111111;
//  PORTC = 0b11111111;
//  PORTD = 0b11111111; 
//  PORTE = 0b11111111;
}

void loop()
{ 
  static char sendbuffer[62];
  static int sendlength = 0;
  char input = 'sennnnnd';
  val = digitalRead(3);  
  if(val == 0){
    digitalWrite(23,LOW); // E0
    delay(100);
    digitalWrite(23,HIGH);
    delay(100);
    }
    sendbuffer[sendlength] = input;
  
     if (USEACK)
      {
        radio.sendWithRetry(TONODEID, sendbuffer, sendlength);
        digitalWrite(5,LOW); // E0
        delay(100);
        digitalWrite(5,HIGH);
        delay(100);
      }
     else // don't use ACK
      {
      radio.send(TONODEID, sendbuffer, sendlength);
      }
     sendlength = 0; // reset the packet
  }

I've been looking through the recommended library but can't see where SPI is defined.

In RFM69.cpp. The SPI interface is hard-coded in that library, so you have to modify it to use another interface.