Hi. I got a problem when running F3. It says it can't run the game because the d3dx9_38.dll file is missing. I have Windows 10 BTW. Anyone can help me to solve this problem?

The game requires DirectX 9.0c: I think you should find the DirectX redistributable package in game's installation folder, anyway you can also download it from here.

I tried to install that DirettX but it didn't work. Then I tried to get the d3dx9_38.dll file on internet. I put it on F3's directory and now it works. Thanks for your help, dr.schliemann.

Now I have another problem in windowed mode. FPS rate is slow although I have a good laptop, which causes the game to go slow in open areas and wide indoor places. Any hints to solve this problem?

Downloading dll files from Internet isn't a safe behavior: you can easily get virus!
Are you sure you installed DirectX correctly from the link I provided? Did you reboot your PC after the installation?
Even if the game still doesn't start, you should now have the d3dx9_38.dll file in your system now: I suggest you to copy it from your Windows folder and paste it into the game's folder instead of downloading it from the web. Does this happen only in windowed mode?
Do you have a dedicated GPU? Are you sure the game is using this instead of the integrated one?

-I installed DirectX from the link you provided; it gave me an error and it couldn't be installed. That's why I downloaded d3dx9_38.dll
-It seems low FPS happens even in fullscreen (funny thing is when I load a radio with the PipBoy FPS increases). Can you explain about dedicated GPU?

Many laptop have integrated graphic units, while others have dedicated one.
Integrated GPUs share the RAM with the system (CPU), hence they generally offer worse performances.
Dedicated GPUs have their own RAM, hence they generally offer better performances.

To save power, it may happen that a laptop with a dedicated GPU still uses the integrated (and less performing) one: in this case you have to force your system to use the dedicated GPU.

Ok. Thanks for your help!