Hi, Eric
Finding size, Look a the ToolPath screen top right corner will show Program Limit's in "Units", Depending on how your machine is set up will determine how the file is treated.
On this Roadrunner G-code file, Being there is no G20 "inch" or G21 "mm" code in the file, It will be cut in your default Native Units "Inch" mode.
If you want to cut it in mm you will need to MDI a G21 or Edit in a G21 in the top of the G-code file in your case.
Edit:Added, If you put a G21 in the G-code file then at the bottom of the code just before the M30 end, You need to put in a G20 to return back to your default "Inch"
unit's, MDI a G20 to set inch mode back if you used it also, Systems using "mm" just reverse the G20 & G21 usage, There Pre Amble / Post Amble settings in the G-code.
Yes, You'll need to use the Scale feature, Setting it to 0.7 to make it fit, I think is about right. see pic's.
To scale it click on the x and Y axis (scale) 1.0 digit's and you can enter a scale value of 0.7 then "Enter".
Hope this Helps, Chip