Which of these is the right way to get an lfo on frequency?
How much the lfo's amount range and frequency?
Should I add [+~ ] or multiply [*~ ] lfo's frequency to osc's frequency value? Or I have to unsig~ it first and then add or multiply it?

[osc's freq\
|
| [lfo's frequency\ == 0~20 Hz ....?
| |
| [osc~ ]
| |
| |
| | [lfo amount\ == range value.....?
| | / . .
| | / . | |
| [*~ ] .' [unsig~ ] [unsig~ ]
| / / / /
| / / / /
[+~ ] ..... or .....[*~ ]....... or ........[+ ] ............... or ........

• .........................?
  | | | |
  [osc~ ] ' ' '
  |
  [*~ 0.5]
  |\
  | \
  | \
  [dac~]

I would do like in the attached image. The idea here is to have full volume output even when the lfo affects the input signal at 100%. So we produce a sine wave oscillating between 0 and 1 (modulated by an "amount" between 0 and 1) that wesubtract from 1, and we multiply the input signal by the result, so the output amplitude never exceeds the input amplitude.

http://www.pdpatchrepo.info/hurleur/lfo.png