How to increase swap memory in OS X? I think my swap memory is hitting its fullest and would like to know how to increase it.

I very often hit my 8GB RAM limits and my memory pressure (as seen in Active Monitor) goes red quite often. When that happens "Memory Used" and "Swap Used" are both almost 8GB, so I guess I would like the swap to be 16GB.

It's so easy to find this info for ubuntu but with OS X I only find links for "how to disable swap" which is not what I want at all.

P.S. Not rich enough to buy a macbook with 16GB RAM.
Swap is issued only when needed. There is no limit so if you have a memory leak, that will crash a program or allocate swap to grow as needed.
Usually the kernel detects and protects you, but worst case, reboot and swap is cleaned each restart.
How are you measuring things to conclude “swap memory is fullest”? It starts empty and grows as you use the system and then cleans each reboot. What value is swap now?