Thanks to all of you.
OK.
How large? I would grab 330 or 1k, something like that?
Not smoke related but still a good idea... On the target (the ATtiny)...
• 10K resistor connected from RESET to VCC
• 0.1uF capacitor connected from VCC to GND as close as possible to the pins on the target
10k as pullup to make sure it is not accidentally sent low by some naughty stray electrons and resets?
The capacitor? To reduce noise?