This mod minimises the role of the Trader. Instead you will use the more realistic trading done with the Harbour Trading and Trading Post mods.
You may have noticed that the Trader will sell you things even if you don't have the gold to pay for them. This exploit makes the game fundamentally unrealistic, since you can stock up on expensive items without having any gold.
Realistic Trading corrects for this by allowing the Trader to only buy, not sell. And he only buys small quantities of a few common items, not bulky items that would never realistically fit in his box. The Trader becomes useful only for the very beginning of the game. See the photo to the right for prices.
Instead of buying from the Trader, you can exchange items via your Harbour and Trading Post. See those mods' descriptions to learn how to use them. Unlike the Trader, Harbours and Trading Posts have no limit on the quantities exchanged, and you can only import things if you are exporting in equal measure.
You will find the game much harder with this mod installed, because you will earn only small amounts of gold from trading. Instead, you will need to balance your expenses and income. If you are completely out of money, you can get some temporarily by fulfilling quests.
When loading this mod from within Foundation, the game will automatically download Harbour Trading and Trading Post.