Hi,
I have a new mini kossel with ramps 1.4 and a heating bed
i have a 12v power supply 20A

Should I need to power the bed from the power supply to the +10A side of the board
And have another power supply wired to the +5A side of the board
Or can I use the same power supply and have 4 wired the the ramp board
Thanks

The same power supply should be able to supply both.

However you might need a fan blowing on the polyfuses, because they do get quite hot and will shut down the power if you aren't careful.

Lots of people replace the polyfuses with an external automotive fuse, plus a relay or SSR to switch the high current bed.