Should I start supplementing with vitamin K in addition to vitamin D3?

You do not have to use vitamin K2 if you are taking Devikap 4000 IU. The use of vitamin K is not necessary if you do not have known deficiencies. The use of vitamin K in combination with D3 is not included in any recommendations or guidelines. The daily requirement for vitamin K is: 90 μg for women, 120 μg for men. In healthy people, it is covered by diet and the synthesis of intestinal bacteria. For example, green leafy vegetables (e.g. spinach, cabbage) contain about 200-300 μg of vitamin K per 100 g of product. More here: https://www.gdziepolek.pl/kategorie/witamina-k