RFM69HCW 915 MHz radio module: Sending a stream of int values rather than char[ ]
You need to send the address of a buffer and the size, in bytes, of that buffer. What that buffer consists of is neither here nor there.

If you have an array of 10 ints you have a 20 byte buffer (since one int is 2 bytes on an 8-bit Arduino).

So you just pass it the address of the buffer (which as an array it is already just an address) and the size of that buffer: 

int values[10];
// whatever to fill the array
RFM69::sendWithRetry(20, values, 20, 4, 1000);


As long as the array is statically created (e.g., a global variable with a fixed number of entries) you can use sizeof() to get the size in bytes:

RFM69::sendWithRetry(20, values, sizeof(values), 4, 1000);


As long as you receive at the other and using the same type of buffer it should be completely transparent.

To keep the system cross-platform and able to run on an Arduino that is either 8 or 32 bits and have them completely interoperable it is best to use variables with a fixed size. Instead of int use int16_t which is always 2 bytes and signed on every platform everywhere:

int16_t values[10];


Or use uint16_t if you want it unsigned.