External RAM (23LC1024) and external Flash (W25Q64JVSSIQ) with Sparkfun SAMD21 i'm trying to extend the capabilities of the Sparkfun SAMD21. My question is, which pins do I have to share? I mean, I understand that MISO, MOSI and SCK are shared, but CS connects each to a different pin, am I correct?
My schematics:

I connect my CS_RAM to the D10(PA18 on SAMD21).
and i connect my CS_FLASH to the D6(PA20 on SAMD21)
You are correct, MISO, MOSI and SCK are common to all the SPI devices. Be sure they are all set up for clock polarity etc. The CS\ line is the select line. If the device is not selected it does not matter what goes on with MISO, MOSI and SCK. There are chips such as the 74HC138 that will give you chip selects with just a few additional pins. 1 pin gives you 2 selects 2=4 and 3 gives you 8 selects.