Endorsement on passport
There is no compulsion for you to get your passport endorsed with the foreign exchange purchased for travel outside India. Should you desire to get your passport endorsed, the bank/money changer releasing foreign exchange would do it.

Visit to Nepal and Bhutan
You can carry any amount of Indian currency while travelling to these countries, but you are not permitted to take Indian currency notes of denomination of Rs.500 and above or buy any foreign exchange for visit to these countries.

Bringing in Foreign Exchange
You can bring into India foreign exchange without any limit. If, however, the value of foreign currency in cash exceeds US$ 5,000 and/or the cash plus TCs exceed US$ 10,000 it should be declared to the customs authorities at the airport in the currency declaration form (CDF), on arrival in India..

How much foreign exchange can be purchased in foreign currency notes while buying exchange for travel abroad?
Travellers are allowed to purchase foreign currency notes/coins only up to USD 2000. Balance amount can be taken in the form of traveller’s cheque or banker’s draft. Exceptions to this are (a) travellers proceeding to Iraq and Libya can draw foreign exchange in the form of foreign currency notes and coins not exceeding US$ 5000 or its equivalent; (b) travellers proceeding to the Islamic Republic of Iran, Russian Federation and other Republics of Commonwealth of Independent States can draw entire foreign exchange released in form of foreign currency notes or coins.

How much in advance one can buy foreign exchange for travel abroad?
The foreign exchange acquired for any purpose has to be used within 60 days of purchase. In case it is not possible to use the foreign exchange within the period of 60 days it should be surrendered to an authorised dealer.