The wikipedia formula does apply, with the obvious change as you have a current output

Load regulation % = \$100 \frac{I_{min-load}-I_{max-load}}{I_{nom-load}}\$

As R1 controls the output current, changes in R1 would linearly affect the output current.

You would need to look at the 317 data sheet to see how temperature fluctuations affect the adjust pin current (which is added to the output current), and how input voltage, output voltage, and temperature, affect the adjust pin voltage (which changes the voltage across R1 and hence output current).

The wikipedia formula does apply, with the obvious change as you have a current output

Load regulation % = \$100 \frac{I_{min-load}-I_{max-load}}{I_{nom-load}}\$

As R1 controls the output current, changes in R1 would linearly affect the output current.

You would need to look at the 317 data sheet to see how temperature fluctuations affect the adjust pin current, which is added to the output current. Also check how input voltage, output voltage, and temperature, all affect the adjust pin voltage, which changes the voltage across R1, and hence the output current.