No. The Lee 100mm filter system will not work on your lens. It is not wide enough to cover the lens' field of view at the distance the filter must be placed in front of the lens due to the lens' built in hood.

If you are using a crop body camera (APS-C or smaller sensor), then the 150mm filters will suffice. If you are using a full frame camera you may or may not get a bit of vignetting when using a 150mm filter system adapted to fit just in front of the lens' built in hood.

Lee does make an adapter ring for your lens that allows their 150mm holder to be used with your lens. You may need an additional piece or two between the adapter ring and the filter holder. (I don't use the Lee system for any 'special case' lenses such as your wide angle lens with a built in hood.)

For more about how the Lee system works with lenses such as your Samyang 14mm and some of the disadvantages and idiosyncrecies it has, please see this article by Paul Reiffer.

You are probably better off (and cheaper) going with a one piece holder designed specifically for your lens offered by Nisi or even cheaper with a modular design that is specifically designed for your lens by Haida.

Nisi holder

Haida holder

You could also try to find a Samyang SFH-14 holder specifically made for that lens that requires special sized filters.

Back in 2014 Samyang introduced the SFH-14 filter holder specifically made for their 14mm lenses. Cokin made three special filters that fit the holder, which uses an odd size larger than 100mm "standard" square filters and slightly smaller than 150mm filters: 161 x 139 x 3 mm.

The filters were:

• ND8 (three stop) neutral density
• ND4 (two stop) neutral density
• Half Blue (two stop) blue graduated neutral density

Due to the limited availability of suitable filters, it seems to have never really caught on. Four years later in 2018 a few of the holders can still be found for sale, but good luck finding the 161mm filters to fit it! They're sometimes marketed as 'Samyang 160 filters'.

When using filter holders with a lens such as the Samyang 14mm series of lenses, one must be careful to avoid scratching the filters with the front of the built-in lens hood on the lens. Multi-piece modular systems tend to have more issues with light leaks that one-piece holders custom made for a specific lens do. The advantage of using a 150mm holder is that there are many more options in terms of what kind of filters are available in that size.